Wow, that picture is pretty interesting, and not what I was expecting. Many yorkies with allergies will have a black-spotted belly, but nothing even close to this.
I would see a Vet Derm for sure if you can find one, they are amazing! Otherwise, I'd ask your current vet to biopsy a piece of that skin and have it sent to a lab for a cytologist to look at. And/or, she can take a skin scraping and simply smear it into a culture container and let it grow out for 10-14 days to see if anything fungal grows in culture.
Also, does your vet use an ointment called Muciprocin there....? That may be good.
So sorry you're going through this, it must be so frustrating!
__________________ ~ A friend told me I was delusional. I nearly fell off my unicorn. ~
°¨¨¨°ºOº°¨¨¨° Ann | Pfeiffer | Marcel Verdel Purcell | Wylie | Artie °¨¨¨°ºOº°¨¨¨° |