Partial Knee replacement failure

Hi
I had a partial right knee replacement in April 2012. My left knee had been partially replaced in 2006.The latest replacement started to be painful about 6-8 weeks after surgery. The pain is on the side of the replacement and one particular spot is very sore. I went back to the consultant and eventually after a course of physio he did an arthroscopy in September as he was worried about loosening. He said he didn't find any loosening but had cleaned it out. I had three weeks pain free before I was back to being in pain. He then tried a lubricating injection saying it was looking like the knee needed a TKR or the knee cap replacing.
I saw him in December and he arranged for blood tests and a bone scan saying he would make a decision based on the results. I had my appointment yesterday and my consultant was in surgery but his registrar spoke to him and he said he wanted to leave it for three months and then make a decision, giving me stringer painkillers for that time. The registrar's words were "we are not fobbing you off". I said I wasn't happy to leave it so long so he agreed 6 weeks. I am at the point of constant pain, struggle to walk up steps and get up from sitting and have had two falls
Sorry for the long story but basically I feel like its a numbers game and they want to wait until after 12 months so the figures are good. Should I go back to my GP and ask for a second opinion with another consultant? The other consultant in fact sorted out the problem on my left knee replacement and-the only reason I didn't go to him initially was I thought I had only torn my cartlidge and never expected to be here
Thank you