She could be allergic to something. What are you feeding her? If she's not already, get her on a natural diet of meat, raw bones, some ground up veg, eggs, and a little cod liver oil each day. 1/4 teaspoon will suffice.
If she's having any milk or dairy, take her off them, pasteurised milk is often a cause of allergies in dogs. They seem to do fine on unpasteurised milk though.
I would cut out ALL commercial dog food, at least until she is grown up a bit.
Its unlikely that it would be fleas still, since you've put frontline on her. Thats pretty strong stuff. It could be mange, if it is