About a week after the sudden onset of PMR with debilitating pain in my shoulders, elbows, wrists and hands, the backs of my knees and the soft tissue at the side of knees started hurting badly too. They are part of my PMR, though I don't know why they took a week longer than the other connective tissue spots to start. At one stage (before starting prednisolone) I couldn't lower myself to the toilet and sitting down and getting up again was a nightmare. As John said, you may have reduced the meds too quickly.