Over the last couple of days we've noticed than anything stronger than a caress is leaving red marks, sometimes welts on our 23 month old sons skin, and after 30-45 mins they fade away. Even a warm bathes left him blotchy red over his entire body. He had been sick in the days before the redness began but it wasn't anything serious. We've tried children's benedryl but it didn't seem to help... Any ideas of what could be happening?