sounds like roseolla measles(baby measles). they are not harmful. occurs between the ages of a few months to about two. one year is pretty average.some babies will run a mild fever. but it is usually gone in about 3-4 days. first time one of my kids had ir, i thought she was having an allergic reacion to a food or laundry detergent. called my mom over and she told me what it was instantly. i have had nine other kids since then and i think they all got it as babies.