Has it flared more than once on any of your kids? If just one flare-up, it sounds viral. Some children are predisposed to developing viral rashes. Sometimes there aren't many/ any other symptoms. But obvs seek medical advice if any serious symptoms. Hope they're all better soon. xx
One of my children had a rash all over their body a couple of weeks ago and was sent home. I took them to the docs who said they had a few cases from the same school first suspected as heat rash. The doctor thought it was an unnamed viral infection. It passed after a few days with no other symptoms. Oddly my other children didn't get it.
Was the rash a bit like mild exzema? I have developed this over the last week or so, but thought it might be a reaction to new (expensive) body wash that I was given for my birthday.
If it is prickly heat these products are excellent, gel wash and after lotion. I've only used them myself but it does say they are ok for children [www.suncaresolutions.com]