DD1 (aged 4) has a rash on her buttocks, but nowhere else on her body. It first appeared about 10 days ago, raised red spots/pimples clustered across her buttocks. It gradually faded after a few days, but tonight it is back, with quite angry-looking red blotches across the top of her buttocks. It isn't itchy. She also has a cough.
Has anyone had anything similar? Any ideas what could be causing it?