It could be anything from eczema to heat rash. My recommendation is to pick up some Curel. I have very bad eczema, and Curel works miracles for me. It soothes the skin, reduces inflammation, and in many cases arrests attacks even after they’ve started for me. My mother’s dermatologist recommended it to her, and she passed on the recommendation to me. It costs about three times as much as every other moisturizer on the market, but trust me that it works wonderfully and is well worth the cost.