What are your other symptoms if any? You said it hurts, if its in the heart area it is possible it is a heart attack. If it is a sharp pain, it could be gas. How do you know your heart is beating fast? Do you take your pulse rate? What age are you? What sex are you? If you are a teenage male it is unlikely to be a heart attack unless you are taking some drugs that could lead to that. What is happening to you when this happens? Are you lying down or exercising or anxious? Are you overweight? Is there a family history of heart problems? All these things are pertinent to answering the question and without the answers all I can say is you need to get checked out about this. Is this the first time it is happening or has it happened a lot over the last year or so? Your doctor will also ask you these questions to make his assessment. It is possible you have a heart murmur, or unlikely but possible an arrythmia. To take your pulse place your 2nd finger lightly on the inside of your wrist and when you feel a beat count it, when you have symptoms, do it again to get a pulse rate. You can also try beside your throat to get a pulse. You need to see a doctor and tell him and he will need to run some tests like an electrocardiogram, and a heart ultrasound, a chest x-ray and he may order a halter moniter for a day, where they hook up a wee electrocardiogram to you and get a 24 hour reading of what your heart is doing. I hope this helps. Good Luck.