my cat pulls at fur

I have cat about 2yr's 8 mos. old. She has had 2 sets of kittens. I notice the last set of kittens she was pulling out her fur on her left paw, when I see her do it I tell her don't do that your hurting your self. She is very close to my husband, And very protective to me. The kittens are gone now, to pet store. But she still dose it sometime. How can I get her to stop? Thank You for your time-Pamela Powell, P.O.Box 300459 Denver, CO. 80203