Have you or the vet ruled out mange? The scabs might look kind of 'block' like, thick & dry.
Just had to inject our kks with worm/mange treatment which has worked a treat, and Murphy has grown back all his hair where he had rubbed it off just above his tail.
Our goat came to us with a really dry,scabby patch on the back of her neck where she was stanchioned (harnessed for milking). After gently picking the scab, I gave her a hard massage with e45 cream twice a day & now you cant even tell where it was!
Good luck...