Cat Over-Cleaning

My seven year old female ragdoll has always had skin problems. We've taken her to the vet numerous times for mange treatment and it seems to be gone now. However, recently she's been licking her legs and her back area (around he base of her tail) so much that her fur is coming out. She's getting bald patches and everything. I've been contemplating getting a cone to stop her from cleaning herself so much but I feel mean doing it. Is there any kind of ointment or something that I can apply to her skin to make her stop licking there so much? She's also licked one spot on her tummy so much that there's a sensitive red/bumpy topical wound. Her name is Ewok and she's a very happy and healthy cat, so I know she's not doing it out of stress. Also, she's an indoor cat and she doesn't have fleas. Anyways, I would very much appreciate any advice!

Have you looked into food allergies at all?

We've been getting different variations of the same brand for her and her siblings since they were born, so I don't think it's that, but I will look in to it.