When I first started vaping and I had quit smoking, I ended up in the ER with my first GERD attack. It actually happened while I was at the dentist, and he thought I was having a heart attack.
I was told by the doctor that saw me ( not saying if he was right or wrong.. just what he told me..) that nicotine can upset the stomach's acids and also cause issues with your gall bladder due to the overproduction of bile. Might want to check in with your doctor, just in case it's something like this. GERD attacks aren't any fun at all and can lead to bigger issues in the future if not managed.