It appears you sustained some kind of muscle injury
which is causing the pain. Try using anti-inflammatory pain killers and see if it helps. You can also apply hot fomentation. Also try to lose weight by modifying your diet and regular exercise. Even a brisk walk for thirty minutes daily can make a big difference. Regarding smoking
, it is nice to know that you are trying to quit. While you are smoking, try to throw away each cigarette after just one or two puffs to cut down on the damage.