Go make an appointment and see a Cardiologist and ask him to do these tests on you, and I mean it.
EKG(ECG) - Looks at your heart rhythm functions
Echo cardiogram - Looks at your entire heart from the inside
- Looks for heart's function during stress(physical activity)
If he finds nothing, then your heart is FINE. Relax then, it might have just been a panic/anxiety/hyperventilating attack.