I have TKR on my left knee in 2013. Recovery was uneventful, and the years have been great with the knee. I am able to walk my dogs, ride bikes, and stay active. Not one issue. Suddenly, last night while sitting on the bed talking on the phone, I experienced a pain level of 10 that seems to be below and maybe behind my kneecap as I tried to shift myself. Since then, I am not able to bend my leg without severe pain. Bending it is impossible because of the pain. I need to either keep it bent or keep it straight - moving it at all is pretty severe pain. Funny thing is, about 6 weeks ago, I went to my doc about the other knee, and he took an x-ray of the replacement knee and said it looked like new. Anyone have ideas? I am hoping to contact my doc this morning about it. Thanks for your help