I am experiencing irregular heartbeat, arm pain and chest pain or discomfort (better by: antacid medications, rest) (side: left) (severity: mild) for around a week. ?

PCP: GO SEE YOUR DOCTOR ASAP. If you don't have a doctor, go to an urgent care center. They can set you up with an MD.

Go to the ER: At 23 I would i=find it remote that you have coronary disease but you could have mitral prolapse. and irregular rhythm and other cardiac issues that should be investigated. Antacids helping is a good sign this could be reflux but you must know for sure. the er can run a short battery of last chest film and egg in all likelihood you will be released and sent to your primary for follow up