About a week and a half after I started vaping I had terrible stomach cramps for 2-3 days. Finally went away.
Unfortunately, I've had stomach issues prior to quitting smoking. About 3 years ago I became very sensitive to raw onions and other acidic foods. Cooked onions were okay, but raw would give me pains like I had the stomach flu. I'm not sure if smoking cigarettes contributed to that.
I still have the uneasy stomach moments, but my chest pains and heartburn have been reduced I believe.