May be a vitamin E deficiency. It's called "crazy chick disease". Weird name, but pretty apt. Some Poly-Vi-Sol baby vitamins WITHOUT iron will help, or Nutri-Drench. I haven't used the baby vitamins in a while so I don't remembed dosage off the top of my head- a search on this site will help with that.
Dosage for Nutri-Drench is printed on the bottle.
You could also get vitamin E gelcaps from the drug store. 400IU strength. Moisten some of her food with water, then pierce the cap and squeeze the liquid out. Mix it up and give it to her. Do that twice a day. It' could take a few days to show improvement, so don't worry too much if you don't see a sudden improvement.
A search for "crazy chick disease" on this site should give you more info too. Good luck.