Itchy skin may be a sign of multiple disorders. It sounds to me like you need a second opinion. For example, mange, diagnosed with a test called a "skin scrape" can be itchy and lead to self trauma of an ear with secondary infection. The causative chain here has far too many permutations to really go into here. See a second doctor and insist on diagnostic tests rather than just treatment trials.
Very best regards,
Patchy hairloss is indicative of a skin infection (bacterial, fungal, or demodex mites), and there is also an ear infection which, since it is not responding to topical medications, is likely resistant to the ear medication and potentially in the middle ear--the ear needs to be cultured and flushed. In an older dog without a prior history of skin and ear problems, an underlying problem such as hypothyroidism or food allergy are likely. I agree with Dr. Goldman, further evaluation is needed. For tough dermatology cases, there are 2 veterinary dermatologists in England, I am not sure how far they may be from your location.
Peter Barrie Hill Phone: 0 117 9289420
University of Bristol, Division of Companion Animal Studies
Dept. of Clinical Veterinary Science
Langford House Langford
Bristol , BS40 5DU
Aiden Foster Phone: ++44 1743 467621
Kendal Road Harlescott
Shrewsbury Shropshire, SY1 4HD
Kimberly Coyner, DVM DACVD