I'm new to raising chickens but not animals in general. I would say she may have an allergy to her feed. In any case I would get a product called "Vetericyn Wound and Skin Care" we call this stuff holy water. It is an amazing product to have on hand for all animal care problems. You should start seeing some improvement in a couple of days. Hint - holy water! If not I would think she has an allergy of some kind. There is no need for anything else while using the Vetericyn. It will kill any bacteria or fungus. You could also put all the chickens on oil of oregano in their water. Oil of oregano has antibacterial, anti fungal, anti parasitic properties and will kill viruses. I put this in my chickens water and they are very healthy. Eggs taste the same. Google it and you will find an organic chicken farmer in PA that uses the same product for his meat raising chickens. Awesome stuff. Hope this helps. Thanks