Rash on my son’s skin

[Pricklypears]

I have no idea what it is.
He's not unwell, it’s not itchy or sore. He’s showing no signs of being bothered by it.
It’s mainly on his torso.
I took him to the pharmacy and they didn’t have any clue, just said to give an antihistamine. Which didn’t really work or do anything , as it’s not actually itchy.

heat rash?

I’m not sure.
I was thinking fungal as I did a google image thing via AI and that’s what came up.
But no idea.