I recall having a similar issue when I first started vaping. Can't remember the exact timeframe but it was approximately 1-3 months after switching. I thought I would have to stop vaping. Instead I did the mouth/nose 'no lung' inhale thing for about a week and everything cleared up, been fine ever since.
Hope it's the same for you, hope that it's just your body getting rid of the old smoking junk and being a little pissy about it.
Hope it's the same for you, hope that it's just your body getting rid of the old smoking junk and being a little pissy about it.