I've had it happen in the past and the simple easy solution is to take of the shirt and get yourself a suntan. No, don't put on the suntan lotion or it will make the nipples burn. Go topless for a couple of days, only putting the top on when you are wanting to walk in a store. Let yourself get the suntan and the Vitamin D you need to keep cancer away and let the nipples heal up at the same time.