Hey Francessca,
Sorry that you're having problems with the yellowjackets, ground bees or hornets, as you say.
I had the big reaction called anaphylaxis that requires the epi-pen when I was in my early 20's, and have avoided them since.
You should probably do the same, because even though it is actually fairly normal for the stung extremity to swell as you describe, no one can tell for sure how bad or how fats your next time will be.
In addition to the epi-pen, it is good to keep some of the OTC antihistamine Zyrtec (generic= cetrizine) because it lasts longer, and faster than benadryl, and is also much more aggressive at blocking the reaction and even reversing it.
My epi-pen had expired a couple of years ago, and I keep forgetting to get it refilled, so when I got stung while clearing the pad for our barn last year, I immediately took 2 of the 10 mg zyrtec and some prednisone we had left over after my wife had poison ivy.
Within 5 minutes of being stung I was already starting to itch all over and get blotchy, but within about 15-20 minutes of taking the pills, it all began to fade, and except for a sore bump on my leg, I never had any further problems.
I did repeat the dose the next AM to keep any late reaction from occurring.
We used the Blackflag Wasp and Hornet spray that sprays 20 feet out and foams to cover the entrance in the late evening when most of them were already back in the nest and they died quickly as it kills on contact and residually.
We used the wally world brand on another nest under and in a hollow cedar tree trunk and it took about 3 applications to finally kill them all.
Please avoid all the up-close and personal methods, we don't want to find out how it went by having an obit posted here.
Keep tractoring in good health!
Thomas