One of mine started licking herself bald, and although we treat ours for fleas often, when we took her to the vet, turns out she has a severe flea reaction. It can be a bite from a flea brought in by me or my partner from outside, or outside contact with another cat. My girl now has to have steroid injections every 5 weeks or so, frontline pro every 4 weeks and also antihistamine tablets twice a day!
It does seem alot, but everything she has to have is worth it to see her more relaxed.
Licking alot can also be a sign of thyroid problems from what I know, but im not 100% sure on that.
Please take her into the vets when you can though, as if your cat is anything like my Spinks, it is horrible to watch her so uncomfortable!
Wiggal x