This may sound a little weird seabiscuit, but in addition to the above suggestions, try putting a tennis ball in a tube sock, fling it over your shoulder and press your back into a wall with the sock ball in between you and the wall. Move around until the ball is positioned over the trigger point(s) and press until the pain subsides a bit. Hit as many trigger points as you can. You may be a bit sore in that area the next day, but the actual deep pain will likely be lessened. Also, resist the temptation to limit your movements - moving and stretching the back muscles that are in spasm will help a lot more.
Good luck to you!
250, 240, 229, 220, 216; 199; 186; 154