Never got an answer but I'll post an update-- turns out she was only hiding in the water when I was around. She isn't sick, she was just terrified of me and hiding in the water. I've been leaving her alone and she's stopped being quite so scared of me. She's taken an interest in food, and has eaten a ton of crickets; the dubias don't move as much but she's snatched a few of those up as well. We'll work up to tong feeding once she's completely comfortable with me.