>How big is the cage?
Fairly large. It was intended for adult ferrets and she has it all to herself.
>Are you doing anything that has scared or traumatized her? It is unusual for a chinchilla to bite.
Not to my knowledge! Most of the time I just let her run around and crawl on me. I'll pet her very gently at times, just grazing my finger over her head and back, hardly touching her spine.
>What kind of toys do you keep in the cage?
Right now she has a stuffed animal as a kind of cuddle buddy. She also has nibblers, wood chews, and a wheel, but it doesn't seem like enough most of the time. What would you recommend?
>How often does she get let out?
At least once a day, for an hour or so. I always feel like she isn't getting enough but I also can't be home all day to take care of her.
>What is her sleep schedule like? Does she get natural lighting? Is there a lot of artificial lighting around at strange hours?
As far as I know her sleep schedule should somewhere between early morning (around 1 or 2 maybe?) to at least 5 in the evening. I know chinchillas are nocturnal so I always try to let her sleep during the day.
>It sounds like your chinchilla is scared of something and trying to find a dark place to hide. It could be trying to find a dark place to sleep. Does she have a hutch or a dark place to go otherwise?
No, she doesn't. Her cage is right up against a full window. Her igloo she climbs into most times to sleep is just a plastic pink one, does she need a carved out wooden home?
Once when she found her way under the bed she was just sitting in the corner, looking like she was sleeping. It did raise some red flags.
EDIT: Now that I think about it I'm not even sure she uses her wheel a whole lot. She's always had some kind of problem with them. I've tried using the usual circular ones like hamsters and other rodents have but she would run too fast in them and cause them to break or fall apart. I've also tried using a saucer like wheel but she couldn't run very fast in that either.