Doctors Tell Mom Not to Worry After Toddler's Febrile Seizure. One Month Later, He Dies in His Sleep (Exclusive)

Lindsay Miller tells PEOPLE she's trying to raise awareness for Sudden Unexplained Death in Childhood after her son Mason, 2, died earlier this year

One month after Lindsay Miller was told not to worry when her 2-year-old son experienced his first febrile seizure, the family faced a tragedy that they never saw coming.

On Jan. 21, Miller's toddler son Mason died after having a second seizure in his sleep, leaving the Oklahoma mom feeling "numb, shocked and in total disbelief," she tells PEOPLE.

The month prior to Mason's death, on Dec. 20, Miller brought her son to the emergency room to get checked out when she noticed he was getting a fever. "I noticed he was breathing really fast and I could tell he was getting a fever. And it was winter, it was December of 2022, and I knew RSV, flu, COVID was out there," she says.

"It was just normal symptoms. He was warm and he could tell he didn't feel good, but there was nothing really serious," she recalls. "We went up to the hospital and they did all the tests and everything looked good, and they just said he had a double ear infection, we were prescribed antibiotics and we were discharged."

Miller, who is also mom to teenage daughter Emery and is expecting another little one in January, shares that Mason "didn't even appear sick" and was running around and playing as they were getting ready to go home.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. 

Related: Pregnant Mom Told She Had Clogged Duct. Then Learns It's Stage 4 Cancer and Given Months to Live (Exclusive)

She recalls everyone "commenting about how happy he was and how it didn't really seem to be affecting him."

Five minutes later, as Lindsay and Mason were heading out of the hospital, the 2-year-old experienced his first seizure.

"He was in a stroller and I just so happened to glance down because I didn't hear anything," she says. "I glanced down to look at him and he was in the middle of a seizure. He had started seizing and his face had turned purple and we were still in the ER lobby when that happened."

"I grabbed him and ran him back to a room and everybody came running in there and immediately the doctor was asking, 'What was he here for?' And I said, 'He was here for a fever and we thought he was sick.' And they're like, 'Oh, okay. It's okay. It's probably just a febrile seizure. Those are pretty common in children his age.' "

"I was panicking. It was extremely traumatizing seeing that happen out of nowhere," she continues.

Miller and Mason stayed at the ER a little while longer to be monitored and were eventually discharged and told to follow up with the toddler's pediatrician the following day.

"They had done some blood work and testing at the ER and everything was normal and we were pretty much told that these are common and they're not deadly. Most children will grow out of them eventually and there's really nothing to do for prevention," she recalls being told. "The pediatrician told us we'd keep an eye on Mason to see if he ever had any more and to make sure that it didn't progress into something more severe like epilepsy."

"The pediatrician told us, 'Yeah, I know it's scary, but it can happen. Some kids are more sensitive to fevers than others and he should be fine.' We're not going to do any other testing or anything until we saw if he started having more issues with seizures in the future."

And for the next month, Mason was fine. "We have absolutely no family history of febrile seizures or epilepsy or any type of seizures," she explains. "My daughter has never had anything like that happen. So it was extremely scary and came out of nowhere."

What seemed like a "very normal day" one month later took a terrible turn for the worse at bedtime.

"He had just turned 2 that week and had started daycare for the first time. He didn't go to daycare that day because he only had a four-day slot at daycare. So he was home with me that day and I worked from home. It was just a completely normal routine day. There was nothing there. I mean, he had literally no symptoms of being sick at all," Lindsay shares.

"After I got off work, he was running around playing with our dogs, and then it was bedtime and I put him to bed and told him I loved him and goodnight. And I went back to check on him and he was falling asleep, but when I went in, it kind of woke him up a little bit. So he looked up over his shoulder at me and I shut the door. I didn't want to wake him up all the way. And I went back out and told my husband, 'Okay, he's settled down. He is going to sleep.'"

"I went in to check on him a second time and it was dark and I shined my light on him and I thought to myself, there's no way he's not breathing," she recalls. "And then I moved the light to his face and he was face down in his bed and had gotten sick, he had vomited."

"I just grabbed him and pretty much lost my mind at that moment and was screaming for my husband and our daughter was there and saw everything. And I somehow called 911 while I was running through the house with him and they were asking me if he had a pulse, and I couldn't really tell because my heart was beating so fast when I put it on his neck, I said, 'I think I feel something.' But my husband was just saying, 'He's dead. He's dead.' And I was begging him to stop saying that, and my daughter was freaking out."

Miller says she tried to do CPR on Mason until the EMS arrived shortly after to take him to the hospital where they "tried to revive him for probably an hour or two hours." While Mason was taken away, Miller and her husband Jeremy had to stay home to talk to the police.

"When they finally let us go to the hospital, we were told that they weren't able to get his heartbeat back and that we needed to make the call to them that they could stop CPR," she tells PEOPLE, getting emotional. "And that was just horrific in and of itself because how do you tell them to stop working on your child?"

"We had to stay at the hospital for a little while because the medical examiner was going to come and they had to interview us. It was an hour-long plus interview of Mason's medical history, which was extremely difficult because they were talking about him in the present terms, 'Does Mason have any allergies? Does Mason have any delays?"And he was lying in the next room deceased."

While also in "total shock," Miller was waiting for answers. "No one had told us at the hospital that when he arrived, he had a fever. No one told us anything. I kept saying to them, 'He wasn't sick, there was nothing wrong with him. I just put him to bed. I don't understand.' And they kept saying, 'We're just going to have to wait until the autopsy and the investigation.' No one told us he had a fever. If they would've told me that I would've maybe put two and two together that this was related to febrile seizure again."

It wasn't until months later that Miller's family finally got some answers. "For five months we had no idea why he died," she says. "It was just so sudden and unexpected. We had no idea. Was it something that we did that caused it? Was there something we missed? We didn't know. And that was probably the hardest part of all of this, is we had no idea why he died."

"We waited five months for the results to come in from the medical examiner, only to be told our child passed away from something the doctors told us was nothing to worry about," she continues. "It didn’t make sense. The cause of death read 'complications of presumed febrile seizure' with a common childhood virus as the contributing factor (coronavirus HKU1). Mason had a fever and common virus at the time of death but otherwise was completely healthy per the autopsy results."

"We felt devastated at the results," says Miller. "It was heartbreaking and left us with many unanswered questions. We were told this kind of seizure was benign and he would grow out of them eventually. We started doing our own research and found studies regarding febrile seizures in relation to sudden unexplained death in childhood. This led us to the SUDC foundation and they have played a huge role in our grief journey moving forward since Mason’s death."

"I wanted to share Mason's story to spread awareness for SUDC, as well as help other families who have experienced a loss similar to ours get connected to the SUDC foundation."

Still, Miller says she did feel "conflicted" in sharing Mason's story as "what happened to him was rare."

"A lot of kids are going to have febrile seizures and be perfectly fine and normal and grow up. And then there are the families out there that's not the case. And I've been able to connect with them and we help each other not feel as alone," she says.

"If I could do anything different, I may have tried to do increased monitoring on my son after his first seizure. I just didn't know. I had never heard of anything like this," she adds. "If I had seen a video like that on TikTok, it may have made me think about different types of monitors you can use on a child. If I could help save any child's life so they didn't have to experience this, that would be great."

As she looks ahead to growing her family, Miller admits there's "a lot of anxiety" but she is "hopeful about our family's future." She also notes that they plan to honor Mason by using part of his name for the baby's middle name.

"We are excited about the new addition arriving soon but it is a bittersweet feeling knowing our family will never feel fully complete again," she shares. "Mason was a special, beautiful child and his memory lives on in our hearts."

For more People news, make sure to sign up for our newsletter!

Read the original article on People.