If you should lose her, I would have your state vet (Cornell) perform a necropsy on her to see what was wrong. Probiotics could be helpful with her watery droppings, but she looks very sick to me. Here is a link for Cornell Vet School...
DE won’t treat an active lice or mite infestation. Can you tell if the bugs have 6 or 8 legs? Permethrin garden dust is usually available in most feed stores. Her poop looks to be pure watery liquid, is that what most look like? Is she eating anything? If not try some soft scrambled egg or mushy...
Can you tell us how old she is, and if she is laying eggs? Any pictures of her and her poop? How long has she been sick? Is she eating and drinking? Have you seen lice or mites on her? I would not spray her during cold weather. If there are mites or lice, permethrin garden dust would be more...