[Ellie May]

I'm with Ann. This sounds odd.
I have no idea what the problem could be and after all this time I think I'd be pushing for a diagnosis. Does the vet think Dolly is under stress from her environment or stress from the healing process due to the spay?

Why is the vet saying that it is stress and it is fungus?
Does the vet think she has a compromised immune system or something allowing fungus to over run everything?

My first thought when I hear crusty ears is mites/mange but if she isn't itchy, that is doubtful.