Some of these problems are from swallowing nicotine. Users of various tobacco mouth products often suffer hiccups or worse because they swallow saliva laden with nicotine. That nicotine will make it all the way to the small intestine before being absorbed. In the meantime, it wreaks havoc in the upper digestive tract.
The vaping question is: Do you GULP your inhales? Do you fill your mouth, then open it wide and glup down the vapor? If you do, you might be sending nicotine vapor to your digestive tract, not your lungs. Do not gulp. Inhale and suck the vapor exclusively into your lungs.
Inhaled nicotine can cause a sharp contraction of muscles at the top of the airway, which has the effect of "taking the breath away" from a smoker. We'll all felt it. It's that "WOW" hit. It's caused by nicotine flowing over the muscles there, which freak out and contract.
If the same happens to muscles along your esophogas, I'd guess heartburn or worse might result. But that's just a guess. To me, the one rule for anyone experiencing this would be "never gulp an inhalation of nicotine vapor".