S.W.
I know you don't want to take him in, but you really should take him to see the doctor. I've never heard of such a reaction and I am allergic to bee and wasp stings. I've also been stung by a scorpion. Definitely give him Benadryl just in case. Do not use Orogel, instead make a paste with baking soda and water and put that on the sting...you can put a bandaid on it to keep the paste on.