Those of us who take benzos for anxiety take pills. You get benzo shots as part of the anesthetics used to put you to sleep for surgery. They are much stronger that way than the small dose pills we take. If you ever read the warning about anesthesia, they can cause adverse reactions, though they are using a combination of drugs along with the benzo. You're not likely to find this kind of reaction from a pill, in other words, but very well might from an injection. I'm guessing the ER doc was using it as a muscle relaxant to get your esophagus to relax so the food would either go down or come out. Whether you had a reaction to the shot or the impulse your body went through to evict the stuck food is something an anesthesiologist would know, but having had surgery twice, I can only say that this is well within the warnings you get and have to sign a waiver for to get surgery.