It's an obsessive-compulsive disorder. My formerly wild boy, Oscar, has that, and he is on twice-a-day Feliway for the rest of his days. His fur seems to be growing back, slowly.

I asked my vet about Feliway instead of anti-depressants, as Feliway contains the cat facial pheromones. My tiny bottle was $70 - but I bought it in June and still have about a month or two left!

She might also have a UTI and licking the area there because it is uncomfy. Let us know what the vet says.