I have felt chest pain when I was lying on my left hand side.  I was awake and not sleeping but only lying. The pain vanished after I while I changed to right hand side. But today whole night has passed and I am still having pain in left side of my chest with a sort of numbness in left arm and both hands. Please tell what it is? Could it be a sign of possible heart attack?  Iv gone through ECG twice a few months earlier and both times it turned out to be ok.

Pleasetell what it is?