There are such things as Zenker's Diverticulum (a pouch / pocket-like formation) and mucous webs that can form in your esophagus, and they can catch fluids and solids until they spill over, or the item dissolves. but they can close up your throat if they get large, and you would be regurgitating everything.
please do a search and check them out on web. an endoscopy should definitely find these, but i'd be sure to print a sheet of info on them, or tell the doctor what you're wondering about, in case a shallow pocket or web is forming, and the doctor gets busy looking for signs of disease (which is what we want the doctor to do!), but doesn't look hard into structural problems also. (i'm going to talk to my doctor on Monday before my endoscopy).
an endoscopy - with a full upper GI and a swallowing study - should find out exactly what's wrong, so i've asked for the other two procedures, also, at the instruction of my "neuro-surgeon", who was looking at my bulging cervical disc problem (who my "ear nose and throat" doctor referred me too, saying they were pressing into my throat!)
so as you can see, i've been round the world with doctors trying to find the problem - this can get COMPLEX!!! :)
BUT, from what i've read, Zenkers can be fixed in endoscopic surgery or open throat/neck surgery, and mucous webs can be opened by common dilation.