forceful heartbeat / inability to exercise

Rewind two years, and I was the healthiest, and most athletic 21 year old you had ever met. For the past two years though,  I have had a forceful heart beat that began one day, and never subsided, not even for a few seconds. All the tests show that my heart beats normally, ie no tachicardia, or anything else, but I feel like my whole body is beating. I can see my heart beat in my chest, and I am constantly short of breath. Any amount of exercise (literally walking on the treadmill for 5 minutes) makes it worse. I just want to be able to exercise again.

This began right after I had several intense treatments of electric muscle stimulation done across my shoulders for physical therapy.

Aside from beta blockers, does anyone have any suggestions for me?

Thank you very much for your time and help!
Trevor

[Jerry_NJ]

You post indicates you have been examined by a doctor, a cardiologist?  What is mean by "..tests show that my heart beats normally,..." are you saying the tests say you do not have an exaggerated or overly forceful heart beat?  If you heart beat is such, I'd think a doctor could detect that with nothing more than a stethoscope.  

Did your tests include an echocardiogram or other test to measure you heart's pumping efficiency?  

Why was a beta blocker prescribed, or are you asking would that help?  Only a doctor can prescribe a beta blocker, none are available over-the-counter.  I'd doubt that a doctor would prescribe a beta blocker for someone with a normal heart beat.  

[trevorschmidt]

Thank you Jerry,

I had an echocardiogram, and EKG, and a chest x-ray (to prove my heart was not enlarged). All of these tests, including the stethoscope test, showed my heart was normal. Though the doctor tried to tell me my forceful heartbeat came from the narrow configuration of my chest. (this is obviously false, as I have never had a problem with forceful heartbeating or exercise before).

The beta blockers were prescribed, and I took them for a few days though they seemed to make it slightly worse, and I didn't want to take any chances.

Thank you again for your help