I'm 42 years old and like to think I'm healthy.  For a little more than a year now, I've been experience a constant ache in my left upper chest and back area.  I'm a worry wart so I immiediately when to a cardiologist.   He gave me an EKG, and ECHO, and stress test (nuclear).  Everything came back fine but I'm still experiencing the aches.  Any ideas of what's going on with me?