What Causes Painful Knee With History Of Total Knee Replacement?

I have pain that started in the knee,it's bone on bone and then the pain went down my leg and this is very very painful can't walk. I am no stranger to pain, I had a total knee replacement on my left knee about 8 yrs ago, I don't. Want another one it still bothers me all the time.But do you think my leg is killing me. I'm 61 yrs old, also have problems with my back including spinal stenosis. Thanks so much bella