Hi, lately I have noticed that my heart has been having an irregular beat. I can rememberonce about one year ago my heart felt like it was going to pound out of my chest after I did a short sprint. It lasted for a good 15 minutes and then went away... Lately I have been noticing that its doing it again, but now it feels like I have a double heart beat. I feel my pulse, it pulsing rhythmically. But then all of a sudden afer about 5 pulses it'll give a small, or tiny little pulse floolwer right away by another pulse... Idk what its about... And when I do a short little 2 minute exercise I can literally feel air like traveling down to my stomach.. Its really weird... Any ideas of what it could be? Do you think its serious?