Have A Hard Knot On Top Of Right Shoulder. Sometimes

Have a hard knot on top of right shoulder. Sometimes no pain, sometimes feels like a rotator cuff issue. Feels almost like there's a vein in it. Doctor said not a big deal. Big deal to me because I love golfing. I can swing the clubs but will pay for it the next day. When I push down it I get dull ache. Any idea?