What is going on with my girl?!

My poor little Mio! I just took her bed out of the cage to check on her because she hasn't been coming to the door lately, or hanging out with her sisters. It looked like her one eye was crusted closed! It just looked like a little black line - she opened it now, thank God. But then she started... I don't know how to put it... throbbing? Like her whole body contracted repeatedly, in a throbbing way, and as I'm holding her, she gets periodic shivers. What in the world is wrong? What can I do?

how old is she? has she been sneezing or wheezing or anything like that? any trouble breathing? is she hairless? can you get a photo? how is the eye now?
and most importantly, did you call your vet?

there's no way to know what's wrong without seeing her and no one to even make an educated guess without more information and a photo or better yet a video.

can you get a video of her?

is she any better now?

some rats will shiver when excited or scared, they can also shiver if they are ill or in pain.

She IS a hairless ratty (or was.. she's growing back some fuzz now) but she seems to be back to herself now. She's the little rowdy one, always getting in play fights with the others. Maybe she was just "kicked out of the club" for being too rowdy - they're all snuggled up now.
I couldn't get a picture of her because suddenly she had all the energy in the world to wiggle and run around.

Also from the looks of videos I've watched, it seems like she may have been having hiccups.

How does her eye look like now? Hairless rats are prone to eye infections and debris gathering up inside the lids.
But if it's just a red crusting, that could be porphyrin. Porphyin is a symptom of stress cause by something, could be illness. Best way to make sure she's healthy is a vet check up.