Hello. Three months back when I was doing some workouts in the gym, suddenly I felt some tightness in the chest. After five minutes, I suffered from shortness of breath. It continued for half an hour. I thought that this is due to overactivity. I have done workouts for almost one and half hour that day. So I thought it is because of it. But later I have experienced similar symptoms, twice in the following month. Then I got a doubt and I visited a hospital. The doctor over there, examined me and said that there is no abnormality in my chest. I was very happy and I was sent home with a huge bill. Now after that I experienced three more similar attacks. This time I consulted a cardiologist and I requested him for an x-ray and echocardiogram. The same evening I got the reports, saying that there is no abnormality in my x-ray and echocardiogram. But still having this problem. Is there any thing else that the doctors I have visited missed? I really feel that there is some problem with my heart.