Constantly stressing any part of the body can lead to damage. Rest is always a good idea. While there is pain, it probably is not a good idea to keep working the area. Let it rest; let the inflammation recede. Maybe ice the area.
Once the pain is gone, then try strengthening and mobilizing the area. There are lots of ways to strengthen and open the shoulders. While Yin Yoga generally works the area between the navel to the knees, you can do Yin Yoga for the shoulders too. Poses like the Reclining Twists with the arms over your head, and Anahatasana (aka Melting Heart) can work these areas. [See Asanas in YinSights for details.
http://www.yinyoga.com/ys2_2.0_yinyoga_asanas.php]
For yang exercises, there are simple exercises like shoulder rolls, neck rolls and the upper body pawanmuktasanas (see
http://www.yinyoga.com/ys2_2.2.7.1.4.2_ ... tasana.php) and more challenging ones such as Down Dog, Dolphin, Handstands, Plank, Eagle Arms and Cowface - these all work these areas. So can some of the standing poses like Warrior 1 and 2.
Of course, for real problems, see a professional: a physio can check out your unique anatomy and prescribe a series of mobilizing and strengthening poses tailored for your body.
Cheers
Bernie
