Could very well be allergies. Is she chewing and/or licking her paws?
First, stop the oatmeal shampoo immediately, and ask your groomer not to use it. It's a myth/fallacy that it helps w/ skin/itchies. Vet Dermatologists tell you to never use it. Use a mild shampoo and/or use one for skin issues like Duoxo (get on Amazon).
For more on allergies and how to treat - read this:
http://www.yorkietalk.com/forums/die...tart-here.html