Blackie has excessive licking problem

Q:Does anyone had this problem with there cat?
Blackie keeps on licking and licking her hind right leg. Her whole leg is partically bare now, I just bought one of those long plastic collar from the vet. I just hope it'll heal. I just wanna know if anyone had experence this problem before and did it heal and if did it come back or did it lead to something else...?
Thanks
Shanna