Wow, you went almost a week between quitting analogs and starting vaping! Very rare!
How much did you smoke analogs? What brand? How long?
When you quit smoking analogs, the tar and crud that has been building up on the cilia lining of your lungs immediately starts to break up and expel. The cilia are normally used by the body to help move crap out of your lungs to keep from getting congested. BUT, tar from cigarettes and other chemicals basically clog up the cilia, and that's why smokers are constantly fighting congestion issues.
So, I imagine over the last week you coughed up a bunch of nasty stuff in the first couple of days.
So, now the lining of your lungs is already returning to pre-smoking condition (Though it takes several months to return to normal)... Then you start vaping, and your lungs get hit with vapor.
Are you getting good flavor with your Ego-T? No burnt taste? Because if your Ego-T wasn't wicking well, and you continually dry hit (Semi burnt taste), I could imagine how that could irritate the lungs.