Thanks for query,
It seems that you are having Anxiety neurosis
If you are thin and lean then also you find and heard your heart sounds
As you are not doing any physical activities or exercise,this may also cause this problem.
Do some exercise like running,swimming,jogging.
In medical science this is called third Itis where the thing you study you may feel this type of pain or discomfort so long you study that topic !
So nothing to worry,develop self confidence and do not become panic.
Ok and bye.