...a few things that come to mind are a few already mentioned. Allergies, Mange, etc. Aside from the oatmeal, there is nothing you can do at home. Perhaps some
Benadryl to help with the itching (1mg/1lb of weight). Otherwise, she needs to see the vet for a skin scraping to rule out mange, to be checked for FAD (Flea Allergic Dermatitis), and any other type of allergy.