One question I have for you is, have you ever had the chicken pox, if not then that's what it kind of sounds like to me, if you have had it but it wasn't that severe of a case you can still get them again. Otherwise is sounds like you have a rash, (probably from an allergic reaction to something), so you should get some hydrocortisone cream like oreowing1 said, and start thinking of stuff that may have just recently changed like body wash, laundry detergent stuff like that. If it persists you should see a doctor.
