If you experience belching, bloating, or burning sensation, it’s probably indigestion and gastric problems. But if you’re going through heart palpitation, discomfort in the left side or centre of the chest, cold sweat, shortness of breath, pain in the jaw, neck, shoulder, arm, or stomach, unexplained anxiety, or fast heartbeat, it might be a heart attack. These are the main difference between gas pain and heart attack. 

Heart attacks can last from a few minutes to hours. One needs to understand that, however, the duration of the heart attack and its severity can change. Therefore, whenever you doubt that you are experiencing a heart attack, call for immediate medical help.

No, it does not. There could be many other reasons that might cause pain in your left shoulder, such as a pinched neck nerve, arthritis, osteoporosis, joint injury, muscle tear, etc. However, if you have shoulder pain and cannot recall any kind of reason for the pain, you must consult a medical doctor and seek medical intervention.