text: Have you ever heard of fifths disease?  It's a little like measles.. very common but.. can be contageous. You can take him to the doctor if that is what it is and there's not much they can give you for it. Treat it like you would poison ivy and give him baths in that oatmeal powder stuff.. it will soothe the itching. But.. for sure I'd get a positive ID on this from a physician.