Actually, by reading the history and response, sounds all fungal and yeasty to me. If it were mange, she should have responded to the ivermectin. Also, the response to the different yeast treatment cremes is a pretty powerful clue.
I wonder, looking at the ingredients of the creme that didn't work and the one that did, if a person could figured out if this were a specific strain that is particularly stubborn. That seems to be the difference in the cremes, the different meds being able to get at the different types of fungus (fungii???).