It does sound like a more serious illness. I'd suggest a doctor's diagnosis first for the boy, though. There are two main drugs that the doctor might prescribe (penicillin or vancomycin) and if you choose the wrong one you'd have wasted your money. There is, of course, always the possibility that it's only a repeat of the minor itching and he doesn't have a serious illness at all ...

It's your choice, really.