I am 21 and am have some what the same thing you all are describing. It happened during the beginning of summer 2010 i went in for a normal doctors appointment. we had been running late because of traffic. so we ran to get there on time. when they took me back to get my vitals they noticed my heart rate was at something like 155. they let me calm down from my rushing and took it again in 20-30mins it was still really high around 130. so they did at EKG on me. the doc was worried about this and told me that i need to have some test done on me and to make an appointment with cardiology as so as i could. so i did. i saw cardiology about a month later. they took another EKG with my heart rate being around 115 and told me i needed to have an Eco cardiogram done and to wear a holter monitor for 24hrs. The Eco cardiogram showed nothing wrong just that i had a very tinny VSD when i was born. The holter monitor also showed my VSD but no signs of why i would have a fast heart rate. they told me to come back in 6months so i did this past Dec. when i got there they took another EKG and said my heart rate was around the high 90's close to 100. The doc told me i was on the high side of normal with my heart rate. he said i should be in the range of 60-80 at my age. then told me to come back in another 6 months to run the tests over again. Just recently i have been feeling palpitations of my heart in my chest. I kinda wish i knew what was wrong with me i am in perfect health as far as fitness goes.