My cat is chewing his back feet and parts of his front paws until they are raw and bleeding. I have taken him to a vet and pet pharmacist with no luck of an answer. Any suggestions?

I cute and nice and animal lover and i am good at cooking and playing cards and play with my animals!!!!!!!!!!!!!!!!!!! I am finally 18 and i am single and planing to go to Texas school for the deaf!!!!!! i will miss you people!!!!!