Very Sharp Pain

In the last week without warning I started getting a VERY sharp (almost "hot ") pain in the upper part of my arm very near but not quite in my arm pit.  It is happening when I pump my arm when running or sometimes when I inhale deeply without exercise and sometimes for no decernable reason, just reminding me it hasn't gone away.  Has anyone experienced this, any suggestions? Carla

Carla, It is very difficult to say what that could be. You may have strained a tricep, bicep or even a lat.  Is there any swelling, is it weak, etc....?  

No weakness, no soreness when pressed either.