your post really caught my eye, because i dealt with something for over 35 years before finding out what it was........and then i think it is possibly a combination thing. i'm probably going to give you 'too much information'. i finally found a couple of other people who experienced the same thing with a few differences. one of those people was my 86 year old uncle. he had his throat stretched (which is something that my GI said could be done). but i digress........
i used to work in a fairly stressful job, and one of the times when i would notice 'this' happening to me (i'll describe 'this' in a bit), was when i was eating in a hurry, and it usually had to be certain foods (which led me to think it was wholly or partly an allergic reaction), especially breakfast foods from fast food joints. poultry products almost always was a trigger, whether eggs, or chicken or turkey, and sometimes fish. thanksgiving developed into an anxiety laced meal. my throat would constrict and i could neither swallow or get what was in my throat back up (and you certainly couldn't deal with it politely at the table). so, i would sit there frozen, not knowing whether it would pass (which it sometimes did, and i could continue) or if i would have to make a run for it to a restroom. if it was the latter, it was a decision that i should have made minutes sooner, because by the time i was on my feet, i was gagging uncontrollably and of course it was now a full blown barf with more coming from below. i hope i'm not grossing you out with this, but if your son reads this and says, 'yeah, that's what's happening', then maybe it will be worth it. sometimes i make it to the bathroom before starting to spew, and those instances sometimes are even worse. the burning in my throat and chest right before upchucking is almost unbearable (what i perceive to be what a heart attack feels like). another thing that made me think allergy was involved, was that the offending lodged piece of food would come out into the stool imbedded in a handfull of goo like snot or mucus. tough stuff, too, because it wouldn't just immediately dissolve in the water. the food would sit there and float wrapped in the stuff.
ok, enough with the gross stuff. whenever i mentioned this to my GI with hopes of finding an answer or a connection to my illness (i have ulcerative colitis), he would say, 'well, we can stick a scope down your throat while we have you under for your next colonoscopy it you want me to take a look.' he said that sometimes the esophagus constricts somewhat, and they have a procedure for stretching it back out.......and it seems to work for a while!!! that is what my uncle had done. that didn't seem like anything i wanted to do. i gag easily, and just the thought of a scope down my throat (forget the stretching) made me leave it alone.
well, fast forward to 2005 when i retired and lost my health insurance and started going to the VA. i don't remember what brought it up, but i think my physician's assistant (not even a doctor) asked me if there was anything else happening to me one day (he's really a good listener). i thought to myself, hey, let's try again! so i told him about this scourge and what my civilian GI wanted to do. he said they could do that (and as a matter of fact, my civilian GI at that time was the hired gun to handle gastro problems there at the VA hospital), but he wanted me to try something first and see if it did anything for me. now, i have had acid indigestion since i was a kid, and have eaten more rolaids and in later years pepcid than i should have. i never associated this with GERD, but he did, and he gave me a rx for omeprezole which is prilosec. since that day, i have had 3 wonderful thanksgivings, many romantic dinners with my wife, many cold turkey sandwiches, and fast food breakfast sandwiches.
my PA declined the kiss and hug that i offered at my next visit, but he smiled when i informed him that he had made one of the most profound changes in my life since da Donna M.............................................
i hope your son isn't as bad as i have described. when i first joined HW, i asked a similar question and got a few responses, but nobody with the full compliment of symptoms as i knew it. but i think it is a combination of GERD and allergy with me. i think my esophagus was in bad shape, and when i would eat a turkey sandwich, bam! i was in trouble. everything i read suggested the dry bread was getting stuck and stuff like that, but i knew that wasn't it. healing the esophagus seems to have been the key. good luck!