Hello,
You can do a search for polymyalgia Rheumatica, or PMR. It causes a great deal of muscle pain and stiffness and is symmetrical on the body. If one shoulder hurts, the other does, too. It often takes awhile to diagnose and often runs its course in about a year. I felt like I had a really awful case of flu--the kind where your muscles ache really badly. Usually when prednisone is given, the pain clears up almost immediately, but you have to continue taking it until the sed rate goes back to normal, indicating no more inflammation.