they are real docs ed, with specialty training, but like with any doc, opinions, advice and experience can vary. i didn't like the first allergist the e/r doc sent me to. my regular physician sent me to the great doc i have now. as far as his advice on use of the epi immediately after a sting regardless of reaction, perhaps is based on your blood test, previous systemic reaction, meaning you are not under the protection of injections, and the belief that continuing systemics could happen, including anaphylaxis. i don't know, it's just a thought.
would i? i might be inclined to inject myself upon being stung IF i were not under the protection of the injections, i wouldn't want to wait for it to happen. i say that because in all honesty, this would probably be 'fear driven' for me. if i were to be stung now, i know that the first few minutes will be a determining factor, if i were to immediately develop hives and swelling, or any other sign, i would use the epi, but that is based on my history. that is just my perspective on it, not advocating injecting yourself upon being stung, just saying what i might do.
we are all different, our immune systems and reactions. you have to be comfortable with your doc and trust that they are giving you the best advice and care for your situation. if it's any consolation, i'd be inclined to get a second opinion from a different allergist.