Overgrooming can be from medical or behavioral causes. I would have her examined by a veterinarian to discuss medical causes like hyperthyroidism, food allergies, and dermal parasites. Once these have been ruled out behavioral causes can be examined. Cats are very sensitive to changes in environment or routine. Once a behavioral causes has been identified behavioral modification and medication can be used to treat this condition. I would address this now before she has the change to over groom and in the process self-mutilate.