Pics or it didn't happen. Similar thing Happened to me a couple months ago too.
I felt anxious & panic , but had no reason to. I work out; and was about to go for a walk to ease the anxiety; strapped on the heart monitor, and Heart Rate was 155.
I checked my BP, and that was normal; but pulse didn't go down after 20 minutes.
So, I went to the clinic, they said I was in fibrulation, and called the ambulance.
after a couple hours of monitoring; still no change - they sent down the cardiologist.
They did a sonogram of my heart, and explained the process of re-setting the beat via the de-fibrulator.
So, they had to take one more look at my heart to ensure there were no clots; they did that by sticking some probe down my throat. They shot me up with Propyphil (the same drug MJ died from) and re-started my heart.
When I woke up, I found some pics on my phone & had a good laugh.
The final diagnoses was Atrial Fibrulation - fairly common.
I think that I did drink a bit the night before which may have had something to do with it.
Good luck!