This is Dr. David. I am reviewing your question now and will be with you momentarily.
frozen shoulder can cause the nerves to be stuck in the same position and can cause weaker muscles in your arm and hand
dupuytren's contracture in the hand can make writing difficult as well.
you should see a neurologist and get your nerves examined and a shoulder MRI scan.
you may benefit from movement of your shoulder under anesthesia followed by physical therapy.
you may benefit from a neck MRI scan to check for pinched nerves.