Getting old is definitely not for wimps. My mom used to tell me that, I guess as a warning and to make sure I did not mistake her gray hair for anything but an indication of her strength and tenacity (I never did, for the record.)
I am currently in a sling with a bum left shoulder (thank goodness it is not my dominant side, is what the

doctor said and I agreed by telling him thank goodness it is not my throttle side!
) I am set up for physical therapy for the next 3 months and a recheck with my orthopedic doc in March. We are hoping to get things strong enough so I can have surgery in the winter of 2011.
Definitely make sure there is not something bigger going on, unexplained pain is not a normal situation. Also, make sure your doc knows about all of the medications that you are taking (for example I take a lot of Ibuprofen, so I have to be careful to take the medicine with plenty of liquids and watch for any signs of GI problems).
If you are doing something that causes you to have lots of muscle pain you might want to talk to someone who can help you to make sure you are adequately warming up and stretching out before the activity and following a nice and gradual cool down time after the activity to ensure you are not stressing the muscles to the danger point.
Good luck,
-v