Is she active during the day or at night?

If she's constantly wandering her cage during the day, it's a sign of stress. As the saying goes, "a hiding ball is a happy ball". Mine hides all day and only comes out at night once or twice to check out what I'm doing.

How many times have you tried to feed her in the past few weeks? If you repeatedly offer food within a day or two of them refusing that can stress her out too.