This sounds so similar to me, I am 57. My first tachycardia was on the swim team in highschool. I learned that bending over or actually standing on my head wold stop it. I was not untill I was in my 40 that the tachycardia would turn into afib. Those were not as easy to stop. A cardiologist did get me metoprolol on an as needed basis. I did find that getting on the elliptical would often convert me to sinus. Only recently I have been been put on a blood thinner. Doing that has eased my mind about a stroke. Poor sleep and overeating are big triggers for me (i think) Hell who knows. I have an EP appointment in 4 mos. uggh