What Causes Sudden Shooting Pain From Left To Right Side?

Hi there, Im a 36 year old male, 6ft 2, approx 180pounds. Ive been having this intermitten pain that comes on for a split second approx 1-5 times an hour, sometimes less. It only last a split second and seems to shoot abit from my left side to my right abit. I have seen a doctor, he has listened to my chest, and I have had an ECG done (not an echo) and all was normal. I do have a history of whitecoat hypertension as they call it and I am an extremely nervous guy. I work out frequently but have not since I had flu about 2.5 weeks ago. This pain happens pretty much whatever it is im doing. Im not breathless, I dont have any other pains. Any advise is appreciated.