Things that help me:

-- When I get huge muscle tension underneath my left clavicle, I roll it out with a lacrosse ball from the center to the outside. Maybe 10 - 15 reps. Very lightly. The first time I did it, I used too much pressure.

-- Diazepam for muscle relaxation.

-- Cold pack. 15 on, 15 off, 15 on.

-- Muscle meditation which I have described in a previous post. One particularly bad day, I did this on my SCM with no improvement until after 20 mins the whole thing suddenly released.

Good luck.