The sling looks good.
I hope she improves with vitamin therapy. I too would work on hydration first, then see if she'll eat for you.
Sometimes it's a slow process of healing.
Keep us posted.
Right foot especially, the nails are quite long and the toes are curling under. Is she walking on her toes and not her foot pads?
Does she have Scaly Leg Mites?
Lice or mites on the body - under wings, around vent, top of head?