This might sound kinda crazy but do you know a vet you can trust? My vet looked at a sample from my cat's ear and saw yeast when he suspected ear mites. I think it is odd that yeast (except female stuff) is acknowledged in animals ( parasites too) and not so much for people. Maybe they can do some tests for you. I believe veterinarians work on a slightly different philosophy that people docs. At least my vet does.