How to help my dog with her allergies?

i have a west highland wight terrier, and we live in florida, on the water. she always itches her legs, biting them to the point where they bleed, and her legs are the only part of her body with no hair, like the front of the legs and the back and both front and hind legs. she bites and licks them raw, and i dont know how to help her. any tips would be greatly appreciated. she is 15-20 pounds healthy 6 year old west highland white terrier female