17-year-old Lydia Parker is now speaking out about the medical mystery that's shocking the nation.
She's one of the teenagers who can't stop shaking and jerking and it's made her life a living hell.
Parker told INSIDE EDITION's Les Trent, "I never have a break from it."
The teenager has a massive bruise on her face that she sustained after fainting and hitting her head.
Trent asked, "What happens when I hold this arm down?
"It just starts on the other side," Parker responded.
She's one of 12 girls from an upstate New York High School who suddenly began suffering uncontrollable body movements that have been compared to Tourette's Syndrome.
Most of the girls who suffered Tourette's-like symptoms at Leroy Central High School have returned to class. Parker, however, has been out of school for nearly three months.
She told Trent her condition came out of nowhere.
"I took a five minute nap on the floor and woke up and I was stuttering and I woke up my mom and she thought I was having an aneurysm or a stroke," she says.
Now Lydia's mom says she can't be left alone and has to stay in the house all day, "It's the strangest thing I've ever seen in my life, I have never heard of it in my life. It shocked me when it happened."
Two of Parker's friends, Thera Sanchez and Katie Krautwurst, made a dramatic appearance on the Today show earlier this week.
Just moments after their interview, Sanchez had to be rushed to a hospital.
So what could possibly be wrong with 12 seemingly healthy teenage girls?
Health officials have ruled out environmental causes and say their high school is safe.
Medical tests show they don't have Tourette's Syndrome.
INSIDE EDITION spoke to neurologist Dr. Laszlo Mechtler of the Dent Neurologic Institute in Buffalo, who has examined 11 of the 12 girls.
"Let me emphasize these children are not faking their symptoms, these are real symptoms but there's no structural abnormality in the brain that we can find," said Dr. Laszlo.
He says the girls are suffering from "Mass Psychogenic Illness," a rare kind of mass hysteria that's a psychological disorder, linked to stress, and usually found in teenage girls.
Parker doesn't buy the diagnosis.
Parker responded, "I think that's ridiculous. I left school in October, I haven't seen any of the girls since."
She hopes to start college in the fall, but only if her nightmare comes to an end.
"Hopefully it'll stop as fast as it happened," said Parker.