Any idea what this rash is?

[dublinruth]

We're away on holiday at the moment and one of the children (age 12) has developed this rash. Started as a small patch on both thighs but is getting bigger and is now on his side too.

I though prickly heat but he says it's not itchy, although it is a bit sore when his clothes rub against it. No idea what to do - pharmacist? Doctor?

That's what my prickly heat looks like, but mine is part sun allergy, so you have anitihistamine? May help?

Only have high grade antihistamines but will try pharmacy for Piriton - thank you.