Now I know how this feels. I have taken my pulse thousands of times a day! I am on a HIV rant right now but it goes between HIV and heart problems. I have terrible palps, PVC's, and tachycardia, I also feel like it is working too hard. I am an RN and do know a little especially with all the heart problems I have had. Hearts don't just stop without a reason...those reasons in young people are rare but is normally long QT and dialated cardiomyopathy that sometimes extreme sports people get that ALREADY have the genetic defect. So you had a EKG, that rules out long QT, the doctor listen to your heart which they could hear sluggishness and such, so your heart will not just stop. I took my pulse so many times I have permenant fingermarks on my neck, this is just HA (easy to say except when my heart starts going). Anyways you will be fine. I worked in the ER and had a lot of people come in with heart probl;ems, ALL the young ones who were actually worried about it, there was NOT nothing at all wrong and they were sent home. I do hope this helps. God bless I will pray for you.