Hi there,
i too suffer from the same ailment you do. I will wake up during the night with pain radiating from my right shoulder down to my hand. I have noticed that the cold night air sets it off. If I keep the shoulder, arm and hand covered with a blanket, I usually don't awaken from the pain. I am a diabetic and have neuropathy, and this may be why I have this condition. My mother does the same thing; she too is diabetic, but she also has rheumatoid arthritis. She doesn't know why she awakes with this pain in her right arm and hand - her shoulder usually isn't sore. After one of these episodes, the muscle between the shoulder and elbow is very sore to the touch. I also have difficulty lifting my arm to brush or blowdry my hair. These episodes take place more often in the winter because of the cold air. When it first happened, it was constant, every night, for about six months. Over the last 10 years, it has decreased in frequency. However, I just had a bout this week due, I believe, to the cold night air. (i live in california where it has been pretty warm at night, but recently the temperature dipped to around 40 degrees.) while I can usually get up from bed and walk around with my arm hanging down by my side to relieve the pain, it didn't happen this time. Every time I tried to lay down to go to sleep, it would start hurting again, which leads me to believe that it is a combination of the cold night air and pressure on the nerves in my arm. Anyway, the next night, I made certain to keep that arm covered with a blanket and warm, and I have had no problems since then. Maybe that will help you too.
Try keeping the arm warm at night--it has definitely helped me.