Strange rash

[rasberryandlime]

My toddler has just developed this was suddenly, otherwise well and no temperature.
Any ideas? No rash anywhere else currently, not sure whether to be worried or not

Has he been sleeping on that side? Holding a cuddly close to his face?
Although actually his ear looks a little swollen maybe?
If he's well in himself I'd give a dose of antihistamine if old enough and watch and wait.

Thanks, no he wasn't lying or sleeping on it, it literally happened in front of our eyes when he was sat up! Anyway I'm guessing it was either some sort of insect bite or allergy (although he's eaten noting unusual today). A dose of piriton syrup and it had disappeared a few hours later!

Slap cheek?