I have a 9 year old rosella that has pretty big bald patches under both his wings, he's been to the vet for multiple tests including beak and feather disease, mites and liver disease but all came back clear. My vet doesn't seem to think it's caused by plucking because there's no irritation, and he gets fed fruit/veg/beans/nuts daily with seed treats, has anyone had experience with this or know how I can encourage the feathers to regrow?