Emergency - Crested Gecko Problem

I've had many cresties, and bred them a few years back. I just got back into keeping them and I'm already having a problem.

I go to mist everyone tonight, and one of my unsexed juvies is looking bad. She isn't moving her legs, her face looks ashy, she keeps gaping at me, and her eyes look somewhat sunken in. I cannot figure out WHAT could be wrong! The other 2 juvies I got from the same breeder are doing fine, as well as everyone else in my care. Just some info:
Everyone is kept individually. Everyone is still in quarantine at this period. I got this little one on Sunday, March 27th. I picked her up from the breeder. All of them have been doing great, and then bam...tonight she's doing this.
She is kept in a 5.5 qt Sterilite tub, paper towel flooring, plastic vine from Walmart, little cap of CGD (changed every other day), little cap of water (changed every day), misted once a day at night (humidity holds well here). I don't have a weight because my stupid batteries for my scale are dead and I haven't been able to get new ones yet, but she doesn't look like she has lost any weight.

I just can't figure it out. Good diet, good climbing space, good humidity, good temps, no chance of impaction, etc. etc. I feel so bad for her. I took her out of her tub and put her and a piece of paper towel in a deli cup and placed her somewhere dark and quiet for now so as to keep her from being stressed. Does anyone have any idea as to what could be going on?