I had a dog that licked like that. Turns out she was allergic to flees. The one I have now has grass allergies. The vet can give your dog a shot to take care of it if it's grass. Flees is a different story.

 You might try rinsing her better. Some shampoos can irritate the skin really badly if they're not rinsed properly. You might also try a shampoo/conditioner with oatmeal ( it can help with itchiness.) And of course, you will want to check for fleas. They also can cause irritation. If none of that helps, you really should take her to the vet. - hope this helps