When your computer mouse is not in the right ergonomic position and you have to reach to get to it, you could gradually be feeling pain in the shoulder blade region. Other repetitive reaching activities can cause this inflammation near your shoulder blade as well. Stretching the muscles of your chest will relieve this pain.
Though it seems a bit counterintuitive, stretching the muscles at the front of your shoulder will take away the pain that you feel at the back of your shoulder. Stretching the chest and the muscles at the front and sides of your neck, and strengthening the muscles at the middle and bottom of your shoulder blades is the recipe for success. Also, be sure to adjust your work station, or your steering wheel, or whatever it is that you’re reaching too far forward for.