Hi There
Yes after reading the details provided by you its highly likely that the pain is most likely due to gaseous distension due to your irregular bowel habit. Smoking also leads to
constipation and irregular bowel as well as increases the risk of coronary artery disease, stroke,
lung cancer and many more life threatening diseases.
Acid reflux also causes
chest pain and it's aggravated again by smoking.
The best remedy for all your discomfort is you should stop smoking first completely and you see the improvement within few days.
It's also advisable that you should follow healthy lifestyle habits like going for daily morning walks for 5 days a week, avoid junk and canned food, include good amount of green leafy vegetables and fruits in your daily diet.
For your constipation I would like to suggest that you should take hot cup of milk before sleep as it will work as a laxative and help clear bowel in morning.
Also consult your doctor personally and get an EKG done to rule out any cardiac abnormality.
For acid reflux you can take some
proton pump inhibitor for 15 days once a day 20 mins before breakfast.
I wish you good health