I have a almost constant pain on the back side of my arm (crampy) in between the shoulder and tricep (x3 days). could this be impending heart attack?

WHAT HAPPENED?: I answered this earlier. A constant pain, cramp and reproducible for 3 days is unlikely from the heart. The referred pain from the heart is usually not reproducible. A continuous pain for 3 days likely would have caused a completed heart attack with its resultant complication by then. It is disconcerting, have it evaluated, reassurance is the key.