Knee pain after surgery

I had athroscopic surgery on March 18th. My Orthopedist told me I would be up and around withing 48 hours. It took almost two weeks for me to even put pressure on the leg. I was unable to return to work for well over a month. I eventually went back to work until mid April when the pain returned. I went back to the Orthopedist and he said my knee was full of fluid again and had to do a another aspiration (This was the fourth). He took two vials of fluid out, more than before the surgery. I also was given a cordizone shot and was told everything should settle down. It is now June 1. The pain is so severe I cry at night. I saw the orthopedist again on Thursday and he told me some people take longer to heal. I feel extreme burning and throbbing in my knee along with with tightness and pinching. Is this normal? I currently wear a knee brase to walk around but it is impossible to work. I am a teacher and cannot stand on my feet for more than 10 minutes. I have been given my kids nothing but busy work for the last month and have done no teaching. The pain gets so severe I break out sweating. I can't go on living like this. I questioned the doctor about a possible knee replacement and he said it was out of the question because there was nothing wrong with the knee yet he said when he did the surgery to fix the ligaments, he found the bone all deterierated from arthritis and had to shave it down. The last set of x-rays taken 2 weeks ago show severe deteriaration of the bone from arthritis. The OS keeps giving me Vicadin for the pain but I keep telling him it doesn't help. I asked him for Purcaset but he will not prescribe it to me. Any suggestions would be greatly appreciated as I can't survive with this much longer.