We had an english bull terrier with similar problems think it was called the Mange don't know how to spell it, is the hair coming out if so may be similar, from what I remember changing the diet to fresh tripe and meat and some johnsons cooling tablets helped it a lot, the vets couldn't clear it up properly and was told it was a common problem with this breed, but the above helped alot, it never cleared completely but did stop the dog scratching so all hair grew back, but it did have the odd reapearance, but cannot remember a lot about it as was about 15 years ago when I lived at my parents. Don't give up to early just try a change in diet and see if it helps.