If you are feeling that still, go call 911 and go to a hospital.

If not, go to a doctor.

I had the same sensation a few months ago and hemmed and hawed and finally went to the hospital. They ran a battery of test and in short, I am fine.

I was hesitating about taking time off work, the cost, etc. but then I realized that it would be far better to be a day behind at work and a little embarassed than it would be to be dead.

I don't regret my decision for a second. You won't either.

Get to a hospital or doctor.

Good luck.