Cat licking fur off legs

Hi, my cat started to lick the fur off his back legs and has moved on to the front legs. I took him to the vet and I was told he had no fleas, but it may be do to boredom or stress. He has moved to the base of his tail and the inside of his back legs. The vet said I could get some natural remedy ( I can't remember what it is) it starts with a T and is a natural ingredient found in turkey. Any suggestions?
Thanks