Synovitis and knee replacement

I had a total knee replacement about a year ago. I have been trying to rehab it patiently but had been riding a lot in the spring ( 100 miles/wk). My knee is burning etc, and I have been told I have synovitis. I have added yoga to my routine but it often seems to make things worse. I've pretty much decided to stop cycling for a while to see if I can get this under control. Now, I'm into the pool for a mile of swimming with little kicking. Has anyone used a "pull buoy" for rehab? I don't use my legs at all. I'm not sure if I should stop everything and just wait. The lack of endorphin kick will drive me crazy. I have also tried pilates once in a while. I'm wondering if I should try PT again?

With a total knee replacement, MRI's are no longer an option so, the ortho is guessing at the diagnosis. The symptoms seem to match synovitis.

I'm surely missing my cycling.