First-Time Mom Diagnosed with Deadly Brain Cancer Just Days After Giving Birth: 'I Still Have a Will to Fight and Survive'

Two days before her first baby was due last October, Kristin Sumbot of Salt Lake City woke up on a Saturday morning with an unusual headache and padded down the hall to the kitchen to get something for breakfast. Before she reached the refrigerator, though, she ran into the doorframe and two walls.

She knew right then that something was wrong.

Kristin's husband, Nathan, 28, drove her to the hospital, where the 25-year-old artist and homemaker was given a head MRI. The scan revealed that Kristin had suffered a brain hemorrhage, so doctors decided to give her an emergency C-section that same day.

Just two hours later, August James Sumbot was born, weighing exactly eight pounds. "We enjoyed those first moments with him so much – he was like a calm in the storm," Nathan, an attorney, tells PEOPLE. "And then we had to prepare ourselves for some very bad news."

A surgical biopsy three days after August's birth revealed that Kristin had the most deadly and aggressive form of brain cancer, glioblastoma multiforme stage 4, typically diagnosed in patients over age 60. After surgically removing 98 percent of the tumor, doctors gave her a five percent chance to live for more than one year.

"We went home and enjoyed our baby – he is such a delight and happiness in my life," Kristin tells PEOPLE. "He's worth fighting for and has helped me to remain hopeful. Some nights, I go to bed crying because I won't get to spend 20 years with my child. But he's in my life today. So that's what I focus on."

Positivity was the new mom's focus long before she received her devastating diagnosis.

At age 17, Kristin, a long-distance runner, suddenly became tired and felt a searing pain in her knees. Blood tests revealed that she had acute lymphoblastic leukemia, a fast-moving cancer that if left untreated would be fatal within months.

After a difficult two-year battle with the disease, she was declared cancer-free in 2010 while majoring in art education at Brigham Young University and devoting her spare time to earning money for cancer research by selling her artwork. In 2012, she and her mother, Leslie Katich, hiked the Himalayas to support the nonprofit global cancer charity, Radiating Hope, carrying Tibetan prayer flags up the mountain.

Now Leslie is once again working as Kristin's caregiver so that her daughter can devote her energy to caring for her new son.

"This is where I need to be and what I need to be doing right now," says Leslie, who quit her job with the Northern Nevada Children With Cancer Association and has temporarily moved from Reno to Salt Lake City. "I never dreamed that we'd be going through this again, but somebody has to be a miracle. Why not Kristin?"

Although her daughter's diagnosis is grim, there was recently some bright news.

"Since starting chemotherapy and radiation, she's had significant improvement in her symptoms and isn't as weak as she was," says Kristin's neuro-oncologist, Howard Colman of Salt Lake City's Huntsman Cancer Institute.

"It's always tough for a patient to live with a difficult diagnosis, not knowing what the future will hold or how the tumor will behave," Colman tells PEOPLE. "It's hard to balance living in the moment with that uncertainty. But Kristin is an incredibly strong person with a positive attitude and a supportive family. It's early in her treatment, but we're hopeful that she'll continue to be responsive."

Inspired by her courage, friends and strangers have donated more than $82,000 thus far to a GoFundMe account to help pay Kristin's mounting medical bills.

"Her prognosis is still crippling, but we're focusing on spending as much time together as a family that we can," notes Nathan Sumbot, who met his wife when she was still undergoing treatment for leukemia.

After the couple married, "we talked about having three or four kids and buying a house," he says. "Kristin's diagnosis blindsided us completely, but we're focusing on the small moments in life. August's first laugh and his smiles. That is what's important to us now."

Barring a miracle, Kristin knows there are other firsts she won't get to experience as August grows up.

"It's crushing," she says. "There are moments when I am overwhelmed. But I still have a will to fight and survive, so that's what I'm going to do. Fight and survive, one day at a time."