I have recently noticed something odd going on with my heart rythm. One day while working, I was crouched down and got this weird out of breath sensation, or something (hard to put into words) about at the bottom of my esophogus, and stood up and breathed in. I also had another sensation in the bottom of my throat and kinda laid my hand on my throat and felt my heart beat normally, then felt 4 hard thumps, two normal thumps and 4 hard thumps again. And also recently Ive noticed walking to the bedroom and laying on my side I feel my heart beating normally, and just almost stop, or beat slowly for 2-4 beats. (with the same sensation) I am really getting worried and wondering what this could be. I am 33 yrs old, 1 pack a day smoker and casual drinker. Any helpful direction or advice would be gratly appreciated.