I was having pain in my upper center back and pain into my chest and shoulder. Turned out there it was...Thank God I walked into an emergency room...a pulmonary embolism was right there going to my aorta. They picked it up on a CT Scan. Not a chest x-ray or blood test. Ask for the CT Scan...demand it. It saved my life. I however have no clue where the clot came from and the appointment for the hematologist is tomorrow to see why my blood created it. I am 29 yrs old...trust me..this can happen to anyone.