I may have missed what product you are using to treat for lice/mites. I would lean toward those clumps being lice nits.
I don't know if I've ever seen skin like that on the legs before. Do the scales/skin feel mushy?
I would work on getting her eating well, direct dose her with poultry...
I agree, I would treat her for lice/mites on the body or even depluming mites.
Since she's not laying eggs, Ivermectin Pour On would be a good treatment for lice/mites/SLM and Depluming Mites. Dose is 0.09ml per pound of weight apply to the skin at the base of the neck, repeat in 10 days...