I am 34 years old with a history of shoulder pain and dislocation.  It started when I was about 18 or 19.  My nephew was a baby and he was getting ready to hit his head on a table.  I lunged forward in a recliner that was completely unstable and dislocated my shoulder for the first time.  Since then it has been relatively unstable.  I have been known to be resting my chin on my hand with my elbow on the table, give a good strong sneeze...and out that baby goes.    It would vary on how often, but needless to say the continued to happen and they continued to get worse.  I was, however, lucky enough to be able to put them back in place myself.  One of the more serious side effects lately is that I have an extremely tight trapezius muscle that will frequently knot up on me.  This causes excruitating pain and migraine style headaches.  Relaxing while driving makes the pain pretty bad because the shoulder will go a little lax and then when i go to move...it twinges really bad and after about an hour (which i drive to work each day and another hour home) I am ready for pain meds.