Let your doctor tell you what's up.
I get spasms in my esophagus that feel like my heart going nuts. Turns out it's from acid reflux. Scared the crap out of me when it first happened. Still does now and then, but with reflux under control, things are better.
Anyway, best to let the medical pros give you the answer.
Don't let the white belt fool you. . .
I know even less than you might think.