Can anyone out there offer some words of advice?

I had a tkr 12 weeks ago. For six weeks I was great. I have wonderful mobility with the knee. At six weeks it started going downhill. When I stand up from a sitting or lying position, the pain is so excruciating. It is a 20 on a scale from one to ten. It goes down to a three or four after about eight or ten steps. The pain is worse every day. They have ruled out my back, which I think he wanted to blame it on and the xrays look fine. I see the surgeon again this week and I think he will recommend a bone scan. I have a cementless prothesis in which the bone is supposed to grow over the knee....I dont' know what the deal is. The pain is across the bottom of the knee and worsens day by day. I have gone back to crutches. The pity of it all is, before surgery I could walk pain free. It was only when I twisted or turned in bed that it was bad. Told it was bone on bone, and after trying a scope in December, I decided it was only going to get worse and that in this good shape, my recovery would be quick......and it was....just great up until six weeks. I am now a virtual cripple. Please help me if you can. My doctor says he will find the cause and it cannot hide. I am desperate.