I Have Knee Problems. My Left Knee Seems To Dislocate

I have knee problems. My left knee seems to dislocate and then snap back in but is very painful. My x Ray showed arthritis. I also had an MRI but my doctor did not tell me anything. With my right leg I slipped on a rug and tore the tendons off the knee. I now wear an elastic brace on my left leg and a big plastic brace on my right. I suffer intense pain but my doctor "doesn't believe" in prescribing pain medication. I take over the counter medication but with no relief. What can I do?
Thank you