Hi Grace – do you know *what* tests were done? Did they do a skin scrape? It’s odd that it’s such a specific patch…does it recur in the same place?
Honestly, after so many visits to your generalist with no answers, I’d be looking for a veterinary dermatologist – they can be found at vet schools, usually, but may be found at local Pet ERs. If you’re in Maryland, I know the vet school in Salisbury should have someone specializing in it. I know UPenn’s vet school also has someone. Search for veterinary dermatology near you.
She needs to be seen by your vet. I know this was posted two days ago, but please get her to the pet ER NOW.