My cat lick herself so much that she is wearing the fur sour on her chin.?

I know this isn't normal grooming and she doesn't have fleas or dry skin. What can I don't to help her?
I BRUSH MY CATS ALL THE TIME SO IT MEANS THEY DONT LICK THEMSELVES MUCH ,HAS IT ECZEMA MAYBE
Obsessive compulsive disorder maybe. Seriously! I know a dog who had it & he drooled so bad that you would have thought he'd be hosed down! He had to be put on Prozac.
Answers:    This is a behavioral problem. Some cats over-groom from stress. You want to communicate to your vet about what you can do because cats can sometimes do this to the point of causing sores.
Why did my cat growl?   I contemplate my kitten is pregnant. ?   Can kittens put away fried rice? She's hungry.?   My vet have told instead of departure my kittens food near adjectives daylight it should be split into 5 meal a morning?