My 23 month old son has tiny red bumps that look a little like pimples on his butt and a little on the back of his left thigh. They're not getting better or worse. They started about 3 days ago and haven't gone away. We thought the cause was that we changed the brand of diaper he was wearing, so we switched it back. I haven't been using baby wipes when he needs to be changed. Instead I have been using water and a cloth, and soapy water when he poops. I can't seem to find anything anywhere online that can tell me what these little red bumps are.