How To Treat Pain Starting From Shoulder Blade,spine Towards Ulnar Side Of Right Arm?

I have a pain that seems to start from between shoulder blade and spine and goes down the ulnar side of Right arm...If I press on the ulnar side of my forearm just below my elbow, the pain subsides some....and doesn't go down to my 4 and 5th finger. It bothers me the most when I drive ...somehow the position is very uncomfortable. I was wondering if it could be muscular or I went to give blood today and they said maybe it's my heart...but my blood pressure and everything checked out. ...I have had problem in the past with my R hand