What Causes Pulsations In Forearm And Abdomen?

Starting about 4 months ago I began having a tightening feeling in my chest above my right breast, and I could hear a sound in my head when the feeling would occur, almost like pinching a rubber balloon. Now I am experiencing a similar feeling in my left forearm (if my palm is facing up, the feeling occurs on the same side as my pinky) , and i can actually see a spastic movement lasting about 5-10 sec. but it is occurring more frequently. I am an athlete; i love running, i am very healthy, i have clean eating habits, and do not smoke. Ever since these things have started i've also noted my abdomen is always pulsating as well. I have an abnormally low heart rate (before going in for a breast reduction in 2010 my resting heart rate was 32 beats per minute) but a normal blood pressure. I am only 21 years old 5'7 and 150 lbs and I feel like these pulsations and sounds I'm hearing in my body are not normal. The only other medical conditions I have had in my past are migraines, chronic constipation (lasted for about 2 years and i still experience bad periods of constipation occasionally)and painful menstruation.