I am a 26 year old male, about 5 feet 11 inches tall, and at 160 lbs. I don’t smoke and don’t take any drugs of any kind.

Approximately two years ago, my heart started pounding very heavily whenever I exerted force or strenuous activity. For example, running up a flight of stairs would cause my heart to pound so heavily and fast that it felt my heart was pounding hard against my chest. The feeling is like my heart is going to explode at each beat. This continued for a couple months, so I went to my general physician. He performed a physical and an electrocardiogram. The physical and electrocardiogram came out normal. The heart pounding continued for a half year or so and then went away.

Now recently, the heart pounding is back, but only when in situations when I am surprised suddenly. For example, if I was sleeping and a loud noise wakes me suddenly, my heart would be pounding so hard, it would feel like it was going to explode at each beat.

A recent incident has also seemed to cause a continuous pain in the left side of my chest combined with a slight numbness to my left arm at times. Two days ago, I was driving on the freeway at 70 mph. A car right next to me does not see me and begins to cut into my lane. I see the car coming at me and to avoid the imminent collision, I serve quickly and use the horn. It was a close call at high speed but an accident was avoided. However, right immediately afterwards, my heart is racing and pounding HARD. A couple minutes later, my heart slows down, but then I notice that the left side of my chest has begun to hurt. For the next two days, the pain on my left chest has remained, and my left arm has a weird tingling feeling. The feeling on my arm runs on the underside of my arm.

Should I be concerned?
Thank you!