I have been vaping now for about 2 weeks, previously smoking for 26 years. The only side effects I have noticed is nightly acid reflux, I have been prone to it all my adult life really particularly when eating rich or heavy foods, but never so much as every night! Searching the web I see I am not alone in this, looks to be reasonably common. I have been unable however to find anyone reporting a direct cause such as PG and so forth. My feeling is it may well be linked to flavourings, so I might try ordering some PG/VG bottles and DIY a bit and try no flavourings at all.
At the moment I am combating this by drinking milk throughout the evening, which is working pretty well although I still can tell my stomach is working pretty hard.
If anyone has also experienced this and found a cure that worked for them I would definitely be interested in hearing about it.