3 year old skin allergy?

[nosleepisevident]

So my 3 year old has never had any allergies at all apart from the other night he had custard for tea not for the first time. As a toddler he got it all round his mouth and a couple of splotches on his chest and when I rubbed it off it was bright red in the exact pattern the food had been with harsh border distinguishing. I phoned 111 and within half an hour it had gone down but got a phone call from the gp a few hours later saying to keep an eye but he should be fine. Today he has drawn over his arms in felt tip, not hard and again when I've wiped it off left with the exact marks in bright red not irritated or raised. Does this sound like an allergy I'm booking a gp appointment just worried that it could develop further into anaphylaxis and a bit confused

Have Piriton with you at all times and give in the event of a reaction but tbh it sounds like sensitive skin,is he very pale skinned?

There is a condition where the skin is so sensitive you can write init and it leaves the mark,can't recall what it's called but it isn't serious iirc.

@MrsPelligrinoPetrichor thanks for the reply. He's actually biracial and very olive skinned and the redness is bright bright red which is odder. 3rd time in a week today and never before just odd