I think I would try giving her home cooked food, mainly chicken and rice and vegetables. And give it to her for a couple of months, As somone else posted it can take a wile to get whatever is bothering her out of her system.
If that does the trick, then pick one food and try switching her. If she starts itching again, stop that food and wait a few weeks before trying a different one.
A lot of people do home cooking for them, you can make a huge batch of chicken rice stew and freeze it in small containers. |