I went to the doctor and they did an x-ray, cat scan and a pulmonary function test. All of them came back good.
As this came on suddenly and has never gone away since even using different equipment (coil, etc) it just doesn't sound like vaping to me.
You can try different things -
1) use a higher PG juice than your using now
2) vape MTL at low wattages and higher nicotine level so your consuming less eliquid instead of DL at higher watts..
3) change the tank your using altogether, or change to a coil made with a different metal.. i.e. if your using kanthal change to SS..
4) make sure your changing your coils frequently and not vaping on dirty or gunked up coils..
5) avoid dry hits, use TC features in order to alleviate any dry hits.
6) that's all I can think of off the top. I'd definitely get a second opinion.