Hi.
Thanks for your query.
Noted the history and understood your concerns.
Smoking and alcohol for such a long time of more than 30 years can cause tremendous problems from time to time.
The frequent motions as you have explained can be diagnosed by the following ways:
Tests of stool for three days.
Tests of blood for liver, thyroid and kidney functions.
Colonoscopy and upper GI
endoscopy as you have
gastritis as well as frequent loose stools.
And CT scan of the abdomen to see for any pathology.
If any of the tests are showing any positive tests, then the ultimate diagnosis being made can be treated accordingly.
If all the above tests are normal then you can be taken as a case of IBS that is
irritable bowel syndrome.
Once a proper treatment gets started you can have a long term benefit and you can then give up smoking and alcohol too.
Cardiac check up must have been done by your Doctor as you have mentioned about left sided
chest pain.
Identify the foods and beverages that instigate or enhance your problems and you should strictly stop them.