DS has had a very light rash on his back and abdomen for the last 3 days, but today it has spread to the top of his bottom and his groin area. He's not itchy and seems completely fine. I can't think of anything that could have caused it, no new clothes, new soap/detergent, new foods (although he has eaten a ton of raspberries in the last few days), and it hasn't been hot (so not heat rash). We are monitoring it for now. When should I be concerned? I don't have any pics because he already went to bed.