Katie Sullivan, 18, had lower back pain for the past month that she thought was from her rigorous training schedule as a gymnast and softball player, according to WPXI.
But just after Christmas, she was flown to the hospital in critical condition, where doctors discovered she had a urinary tract infection and that she was in septic shock.
"When they did the testing, they found she had a urinary tract infection for about a month that actually caused a hole in her kidney, which caused an abscess in her liver into her back muscle and behind her kidney, and she was in septic shock," said Katie's mother Shannon Sullivan.
"She's a perfectly healthy 18-year-old who on Sunday was fighting for her life," she added.
Katie's parents say she is finally showing signs of progress.
"For the first time today, I asked her if she wanted to go home and she shook her head yes. They asked her if she was in pain, and she shook her head no," said Katie's mother.
Doctors believe she now has a long road ahead to fully recover.
But the family has one warning -- don't ignore back pain.
"Even if you think it's nothing, please get it checked. Because I never in a million years, and I'm a nurse practitioner, did I think I'd be here watching my daughter being intubated, in renal failure, and being given a dire diagnosis at 18," said Shannon Sullivan.