There has to be help for her. Gosh 3 years old, she is so young, she deserves to live a happy life.....
Maybe her immune system needs to be boosted as well to help fight the infections. What food does she eat? Any supplements? Have you tought about feeding her some Coconut Oil daily? I don't know if it will help, but it can't hurt, there is a lot of healthy benefits associated with Coconut Oil.
Also, Aloe Vera Gel (orally) is also suppose to help boost immune systems.
Aloe and Pets