Why is my cat going bald?!? PLEASE HELP!!!?

My cat, who is about eight years old, has lost a lot of weight and has licked most of the fur off of her arms, legs and backside. We recently took her from the home where she had been living and moved her into a house with seven other cats. We’re not crazy, we just didn’t have a choice. She is still acting normally. Also she will kill you if you take her outside. She’s violent outside… inside sweet… outside violent. Anyway, she looks pitiful. Is it just stress? Also, I have recently taken her back to her first home where she only has one other cat. Will her problem clear up. Also… it’s not the I don’t feed her… she has food in her bowl most of the time and she eats. HELP MY CAT PLEASE!!!