DD is out of a nappy except for overnight. For the last month or so, she has been getting red spots on her buttocks, which I assumed was nappy rash - or perhaps a reaction to wearing a nappy during the heat. Everynight before I put her bedtime nappy on, I cover her bottom with sudocream. Yesterday one of the spots got much larger. It is very red, and seems to have a "lump" under it. It doesn't seem to bother dd, but she doesn't like me to touch it. Any ideas what this could be, and what I should do about it?