I had total knee replacement surgery three weeks ago and am having a similar experience with recurrent pain -- as well as inflammation/swelling -- seeming to be getting better, but then getting worse again. I often feel just as you do too that my overall level of pain and range of motion are simply regressing at times, despite my keeping up with my physical therapy routines, which is disappointing, if not cause for some intermittent despair. I'm surprised just how much inflammation/swelling remains and how tight and restricted my joint still feels three weeks post surgery.