Tucker is licking his hair off again and has a RASH!

Perhaps you could consider one of the Bach Flower Remedies? I do know of a conventional/homeopathic vet who treated a cat who over groomed to the point where the skin was sore. Initially he treated the cat with conventional medicines but nothing worked. After taking the time to discuss the cat's history with its owners he found out that the cat had literally turned up on their doorstep some months earlier and 'adopted' them. He then realised that the cat was 'grieving' for its past life and owners and treated it for grief with homeopathic remedies. It stopped excessive grooming by the next day.