Dull pain in right shoulder that spreads down to arm?

For about two weeks I have been having on again off again, dull pain in my right shoulder that spreads down to my elbow and then to my wrist. It's not severe by any means, just dull most of the time and occasionally very painful. Like right now my shoulder hurts and my hand and fingers feel tingly, but they are not pale. I can move my arm all around without pain It just hurts. I have injured the rotator cuff in my left shoulder and know what that feels like. I am left handed but work at a kennel where I walk dogs all day, and almost everyone pulls on the lead. What is this and what can I do??? I am trying to be tough about this, but sometimes the pain is bad. Any information would be wonderful. Thank you very much.