I suspect one of my chickens has favus. A white powdery substance on her ear lobes and loosing feathers especially on tail and bottom. Otherwise acting fine. I've read treating it with with clotrimazole, which I just happen to have but how often and for how long? Any advice? Also was thinking of cleaning the coop with some vinegar and tea tree oil solution. Any other thoughts? Cider vinegar in their water maybe? Cheers!