My younger brother, who was born with a GI birth defect, and as such has no motility in his esophagus, has suffered from this issue for
years. The whole lot of us has or has had chronic sinus
problems. For my brother, I know mucus plus an excellent gag reflex generally makes for a bad time (and yes, he does have the GERD as well).
I've been taking the Guaifenesin type product to thin secretions, and I honestly think that has made things worse for me, at least as far as the vomiting.