Sounds like an allergy to me mate. Take her to the vet for medication, then most likely you will be given some medicated shampoo that will have to be done every couple of days for a short while. also take note of everything she eats, your vet will want to know this. you will probably find it will clear up quickly, the hardest thing is finding out the cause, which could well be food related. Again your vet will be able to advise you the best.

Hope she gets better soon, and post a pic of your girl, I'm sure we would all like to see.