Dear Addy
The licking is probably the Cushing. Apollo started licking one paw so much the hair is off and I had to squeeze the ingrown hairs out of it.
The white pimple on Zoe's tail is part of the Cushing skin problems, it could either be the calcium deposits or the ingrown hair. Apollo has them all over his belly and his tail. He also has dark skin batches. I hate it.
Wish I could be more help.
Hugs Sonja and Apollo