i kinda know the feeling man, one of the first times ive smoked multiple bowls out of a gravity bong i swollowed a little smoke and ended up sitting on the couch, i can usually feel it coming because i just sit there and dont say anything, i got up and went to the bathroom and threw up, came out and sat for awhile went backa nd threw up again, it really sucked because i was so fuckin blazed i just wanted to chill. i know how you feel man it can really suck.

but lemme say this, dont give up man, you could make a bong yourself and test it out taking small rips by yourself so your not around people when it happens and maybe build up a tolerance to it. because to not smoke out of a bong or a gravity once in a while really sucks, they get you really high.