DS has a rash on a wasp sting from a week ago?

[NoCapes]

DS1 is 7 and was stung by a wasp last Saturday, the sting was on his neck just under his earlobe
He removed the sting himself and when he got home I gave him some Piriton just as a precaution because he's never been stung before and he's allergic to a few things

All was fine although the little dot didn't really go away, but just in the last few hours he's developed a red rash around it, it looks a bit like hives

It's been over a week so is it likely to be anything to do with the sting at this point, or just coincidence?
Do I need to do anything?

Bump

I would keep an eye on it and i would give homeopathic apis 30...but that may not be your thing. High dose vit c is natural antihistamine so you could read about dosing up with this. If rash spreads would get it checked out. I had a mosi bite became hot and red and spread to my whole lower leg. Suspected celulitis developing. A few doses of apis and plantain pack for 3 days and all back to normal.