My 13year Old Daughter Got A Rash On Her Chest

My 13year old daughter got a rash on her chest belly and back about two weeks ago it is a little bit itchy but not itchy all the time. it is small red lumps not too lumpy not too round more oval shape, her skin is red looking, she does not seem to be feeling sick except she has been constipated, but that might not be connected. do you know what this could be??