Well, good to know your vet is not suspecting allergies. As that is more difficult to treat than the mange. Although mange is a pain in the arse to deal with too..its at least more easily managed I think. Maybe the lesser of two evils I suppose.
It sure looked like an allergic reaction to me...in the pics...but...you never can tell. I'm not a vet..and I've never claimed to be. LOL
You did your OWN skin scraping? Now THAT is devotion !