Sometimes no matter how hard we try to help, something is just wrong inside that we can't help. Try to keep her as comfortable as possible. Best wishes.
Sorry you didn't get much help. Symptoms sound like either Mareks or a vitamin deficiency. People use liquid polysol vitamins made for infants. I like vital livestock vitamins. There is also one called chick saver found at tractor supply stores. Hope this helps get you a few more opinions.