Sob, tightness in chest and under ribs. feels like need to burp. if not heart attack what is it?

Gas: Most likely you are 'full of hot air'. Can try simethicone four times a day and see if it helps. Other things are possible too. Stop smoking!

I see you are: Diabetic and smoker. 2 risk factors for coronary artery disease. If overweight then, 3 risk factors. I will r/o ischemic heart disease first with ekg and stress test. If negative acid reflux with esophageal muscle spam a possibility. See a doctor asap.