Hopefully it is ringworm/mange. The other option is a behavioral issue...which could be stress related or physical. try getting some athlete's foot cream (same med) and using it for a week. If there's no improvement, do as haley said and take her to a vet (oh, don't put the cream on any open sores).
I used to own a cattery and if your kitty is indoor outdoor both it could be she's picked up ringworm which is a fungal infection people can catch. Id follow hayleys advice and see a vet to be sure its not either an allergy or ringworm.
Is she a tortoiseshell calico? My cat did this when she was younger and I was told it is because they are very high strung and anxiety ridden. She eventually quit doing it but I just had to remind her to quit constantly. If she continues, she may need kitty drug therapy. :(
I think if she keeps on licking the spots until the point that they keep bleeding, you should take her to the vet. If this is persistent behavior, you should go to the vet.