I had the same experience when I dropped from 9 (comfortable) to 8 (some pain returned). I went back to 12 for five days and am now back at 9. I think I'll stay here for a couple of weeks and then try again. The "lowest effective dose" seems to change as the PMR slowly changes, so we can creep downward very slowly. It seems to me that reducing swiftly is not worth the pain, and instead I am trying to mitigate the negative effects of prednisone with supplements and exercise.