Has your dog had a good skin scrape done?
Have they cultured the skin on the areas effected?
What meds have they put him on any meds or given him anything while at the vet?
Hello, it is quite possible that your babay has a case of mange and it shoulkd go a vet for conformation. The vet needs to do a GOOD skin scrape meaning that when they scrape the skin they need to bring blood to the surface while they are scraoping so that the mites will come off the skin with the blood onto the microscope slide. She could have a case of mange and the black sposts are due to the infection on the skin caused by the intense itching and the sores that go along with it. I had a client that had a very similar case like yours and she had also been to 2 other vets who totally missed the mange and the poor dog was just put on some antibiotics and steroids. Her dog got worse until the leasions started to open up and hget bacteria in them. Finally after she came to us we discovered the mange and were able to treat her. Her poor dog suffered through 6 months of being misdiagnosed but not she has completely recovered and looks great.
If once at the vet they do not discover mange on the microscope slide I would consider having a skin biopsy done to try and determine what is causing this to your dog. Once the biopsy is back your vet should be able to come up with a treatment to help your dog. You may just want to consider treating her for mange at this point and either get some dip from your vet or some injections of Ivermectin and the dip to see if that helps any. Hopefully that will help her out alot. I hope this helped some but if you need anything else be sure to let me know.