When Kevin Doyle's daughter was 2 years old, she was spry and energetic, but in the space of a week, she went from jumping and skipping to not being able to roll over in her crib without help.
Doctors believed it was a virus that would pass, Doyle said, but now at 7 years old, Mercy Doyle is struggling with the same symptoms.
She suffers from tremors in her feet and deteriorated muscle coordination. She is unable to walk or crawl.
"We've been through four different chemotherapy treatments and some other similar-style stuff that people use for very strong arthritis," Doyle said. "We've had a great collaboration of doctors … and they just cannot seem to come up with any type of way to move forward."
Her parents have traveled anywhere they can for medical treatment; and neurological specialists from across the country have consulted on Mercy's case.
"Basically, they said they know it's an autoimmune thing, but she's unique to herself," Doyle said. "There's just no diagnosis for her."