I have this really sweet austrolorp hen named baldy, and her feathers keep breaking off and falling out. Her skin is not irritated, and she does not have mites. Does anyone know what's wrong with her?! She's been like this for a year and a half!!! Other than the obvious lack of feathers, there is nothing wrong with her. She eats, drinks and lays fine. And it's not feather picking because my chickens are free range and fed a very nutritious diet. Can anyone help?