Did they do an echo? One thing I have experienced was that my heart really pounds when I am tired and laying down. Dehydration
is another thing that makes it worse, make sure you get rest and plenty of water. Does your heart feel like it's flip flopping or banging inside your chest? Thats how mine feels. Just a note to help, if it starts doing it for more than a few seconds bare down like you are trying to have a bowel movement, the extra pressure will "kick it" back into right rythm. Make sure you get echo, a lot of people have pals and they are not serious but your Dr needs to know for sure.