PLEASE HELP! Baby Road Island red collapsed?

[DatRissi]

My poor little Road Island red (that I got from the Tractor Supply store) collapsed about 20 minutes ago and won't open her eyes. She is still breathing, just very slowly. We moved her to a separate box, and she croaked once, but now, she is just laying there, breathing. She won't open her eye if we touch her. I'm worried because she is suffering and my other Tractor Supply chicks and my UK line chicks from the breeder (Who are in a separate brooder but were in the same one for a night) might get sick from her, too!
Please help!

 

[DatRissi]

UPDATE: It's as if the chick is paralyzed (She still stirs occasionally, just very little)! We picked her up to give her water, and her head just slumped over. She can't move. She is still breathing, but it has been at least an hour and a half. What is wrong with her?!

 

[DatRissi]

Final update for this chick: Before she died. yellow discharge with specks of blood spilled out of her vent, then she stopped breathing. Can someone give me a diagnosis, because I don't want any other chicks to die slowly and painfully like her.