11 week old chick not eating/acting lethargic

[Jujubara]

I have a Cream Legbar pullet that was fine up until today. She's hiding and not eating very much. I was able to get her to eat some oats with Powerade. It's all I have on hand at the moment. Her crop is pretty empty and her poop is practicality non existent- mostly water with a bit of white. No mites, all other chicks and adults are fine. I've looked up a ton of stuff, but it mostly points towards young chicks. Any help is appreciated.

 

[Jujubara]

They've gone in to roost for the night. She ate and seems to be a bit better.

 

[Jujubara]

Bump.

She was a bit better today, but she has cold feet. Anyone know what could be the problem?