Depending on your age, and if you already had the chicken pox, there is a possibility of it being shingles, a form of chicken pox, usually brought on when a person is older and lacking in vitamins. Mind you, I have seen people a lot younger get it. Have it checked by a dermitologist. May be something as simple as changing the laundry detergent you are currently using. Maybe a rash from rubbing up against a certain plant. There are several reasons. If you can't get to a doctor, I'm sure a pharmacist can help. You may just need some cortizone cream, noxema, a name brand contains small amounts of cortizone which are safe and might just do the trick