Hi i am 36 yeas old male . height 5ft 10 inch and weighing 90 kgs. I am having a low pain in the upper left chest , belly , lower abdomen , some time spread over right side  for last 2 months . It is not always present ... come , stay for a minute or two than fades away.... The pain is so smooth  and dull some time that if u are busy in some work or chatting with some body  you will not feel it. but some time it is very sharp . and it is going away with consumption of antacids but comes back  if i stop taking it .... i had a history of moderate smoking for last 12 years but quieted 4 months back.
It could be acid related pain. Would suggest continuing to abstain from smoking and if you consume alcohol reduce intake and if possible abstain from its intake. Avoid spicy food and fatty food. Take antacids for sometime with above and then if still you have pain see your doctor who may advise you to have an endoscopy ± ultrasound of your abdomen.