What is wrong with my pet rat?

About a month ago I bought a little pet rat and she has started acting very peculiar. She has started hoping along instead of the typical scurrying, and she sometimes seems disoriented. She has lately started chewing the bars of her cage, but not in the gnaw it down way. She's still very friendly but has been acting weird. She will occasionally wobble back and forth when sitting still, as well. She also seems to have a tick every now and again while she's wobbling. I've had several rats as pets and never encountered it, any helpful advice would be greatly appreciated.