Hey Annie,
As you've noticed, that there is "something wrong with her", and you have her in a warm, safe, protected place, she's eating and drinking - all good. This IS "veterinary medicine" - they can't tell you what's wrong, so you have to go by signs and intuition. There are probably thousands of possible explanations for her behavior - but you may just have to observe her for awhile - in that warm, safe, protected space - until it manifests itself or resolves on its own - which many things do! You are doing right to isolate her for her, and your flock's, protection. But you can't expect anyone to give you the answer to what's wrong with her at this point with the information you've provided, or noticed. It isn't a perfect science and it ain't magic! Check the obvious things - is she crop-bound, or egg-bound? Any external signs of injury? Supportive care and observation are the best that could be recommended at this point, I would say. Good luck!