I might take her to the vet to test for parasites if nothing else.
In the meantime I'd make a mush of her pellets, and add just a drop of honey or karo syrup to make it sweet for her. Try to syringe feed her.
I'd also be concerned about tooth problems and ask the vet to x-ray at the very least, examine under isoflourane if she's stable enough.
Good luck to you!