they could be various reasons to it one could be nerve
compression on the position you are sitting on, another is heart attack
which you have already ruled out
third is deficiency of vitamin b12
in the body could result you to feel that
fourth could be some problem in the brain which causes that numbness
in both hand and leg
fivth is low levels of calciums in the body could result in above complaint
sixth sometimes diabetes
can present in that way
seventh - some drugs can also cause the above complaint.
i would suggest you see a physician to rule out by doing tests and further treatment.