Ok, a little Epipen education.
1) If you are truly having an anaphylactic reaction, as apposed to severe sting-site swelling, it is a bodywide hypersensitivity reaction. You could be stung on the toe and have hives all over your body (bad sign), angioedema where some part of your body puffs up (really, really bad) or your throat could swell until you cannot breath (you get the idea). Any of these last 3 are LIFE THREATENING emergencies. The chemical processes that are in motion during anaphylaxis can last 3 or more days... an Epipen lasts 15 to 20 minutes. An Epipen is a crutch to get you to the hospital so that medications can be administered to hopefully contain the reaction. You might get to go home in a couple of hours or you might spend a few days in the hospital depending on the severity of the reaction.
2) An Epipen is a dose of epinepherine, a drug that can have significant side effects. It can even have life-threatening side effects under some circumstances so it isn't something to play around with. Talk with your MD and see if he or she thinks you actually need to have an Epipen.
3) They shouldn't be used for a routine sting (ie- you have no itching or tightness of the throat, no unusual swelling of a non-stung site) that could easily be treated with an over the counter antihistamine.
Always talk medical situations over with your physician, they are trained to take care of us and most of them do a great job. Any time you are stung be very aware of what is happening to your body. The degree that a person will react to a sting is never 100% predictable but normally the longer you go without a problem the less likely you are to have a problem but there are no absolutes. Normally problems will progress in steps (ie- hives, then worse hives, then angioedema, then full blown anaphylactic shock) but, again , there are no absolutes. I know of people who have gone from "wow, I'm a little itchy" to "call 911" in one step.
One last thing, Benadryl or any other antihistamine, will have a dose for adults on the bottle that should not be exceeded. More will typically only increase the side effects.
Y'all be careful out there.