I am experiencing chest pain or discomfort (better by: anti-inflammatory medication, antacids, rest) (quality: burning or stinging) (side: left) (...

A little too vague: It sounds like you might have GERD (gastro-esophageal reflux) wherein some of your stomach contents goes back up into your esophagus. The laymen's term for it is "heartburn" though it has nothing to do with the heart. Simplest way to confirm that is to get a bottle of a liquid antacid and gulp it down (1 -2 capfulls) as soon as it happens again and if U get almost immediate relief, voila.