I think whether or not you cough up stuff from your lungs depends on HOW you smoked. After 53 yrs of smoking, I waited and waited to start the coughing and clearing process. Didn't happen, and I thought on why in the world would I skip this very important healing function.
There two things that might have contributed: 1. I was a "shallow" smoker. Very seldom inhaled deeply. Think on the old movie star's, Bette Davis, quick puffs and you got me. 2. In the middle of those 53 yrs. I played 25 yrs of quite a lot of tennis. 2-4 hrs, 3 to 4 days a week running around and panting on those courts will certainly help clear out whatever is in your lungs.
I did catch a cold around Easter, nine months vaping, and coughed, put nothing came up. Fever and wiped out feeling for a week, and another week not up to par. Maybe it wasn't a cold, but this old bod adjusting. No way to know.
Anyway, it's been a yr. now and in another few mos. will turn the BIG "7" "0"! Ain't going to worry "boud" it one bit.
......The knees tho may be cause for concern.