Yes I totally agree with you oceangypsy. if it's caused by yeast it will be readily responsive to the antifungal treatment within 3-5 days. However when the infection persists, then it might mean something else.
Please keep in mind, that animals that have fair skin on noses and ears can develop skin cancer there later in life. It doesn't hurt to put some sunscreen on if they are spending time out doors for extended amounts of time. Please look for a natural type of sunscreen, esp if being used daily.