What u suffering is most probably Panic disorder.This is characterised by episodic palpitation
,restlessnes,choking sensation,sensation of heaviness over chest,tingling
numbness in hand,sweating,weakness all over body,and feeling like any moment i will die.And all investigation reports comes normal.
If u have any of this along with shortness of breath
then most probably u suffering from this which is curable and needs proper course of treatment.
For proper diagnosis of this pls meet personally to any of nearby psychiatrist