Welcome to YT! I am sorry that you are having such problems with her skin. That can be tricky to figure out. Can she have fleas? What shampoo are you using??? Yorkies have hair instead of fur so they need shampoos that will not dry out their skin.
What are you feeding her?? Corn, wheat and soy can cause severe allergies. I would definitely avoid those in whatever you are feeding her.
I would do whatever you have to do to get her skin problems under control. Poor baby! She must be miserable.
