Yep, wasps are assholes
Got stung on the wrist myself at a beer festival a fortnight ago. I played nicely all weekend (no swatting!) but got stung anyway. I’d include the picture if I could, but El Reg’s below-the-line stuff doesn’t support that.
Wasp sting treatment? Insect bite creams like Anthisan are good. Or failing that, topical application of something mildly acidic like lemon juice. Or application of ice. You can imagine I had lots of trouble finding ice and lemon at a beer festival at a pub.