what tests have been done by the vet? Has he done a skin scraping? wow it could be so many things, but many of the treatments you have done should have worked, mites, ringworm, dermatitis, ect. However the thing that caught my intrest is that you say you switched to a low protein diet, that cannot be a good thing... Many dogs, including mine, have allergies to the low quality carbs in many dog foods, wheat, corn, brewers rice, ect.. are all bad things and highly allergenic. Have you tried a high end grain free food? I like Orijen red meat, or innova evo red meat, What is the food that you are feeding? It cannot hurt to try a switch to a grain free, or even raw diet, maybe with some oil suppliments? Good luck keep us posted!
I prefer my people to wear fur..
Gonzaga's Lady Perdita "Lady" CKC Yellow Lab
Adoptee Gucci super fuzzbutt
Adoptee Prada crazy dog extrodinaire
Tickles Tortie cat the owns my daughter