Extreme tailbone pain?

I am 21 years old and I have chronic tail bone pain. It has worsened in the past 6 months but has been going on close to 2 years. It has gotten to the point that when I sit and stand up the pain is so severe that I get teary eyed. What is wrong? I am not sure if it is arthritis or not but if it matters I also have chronic knee pain. When I went to my doctor she said that she wouldn't give me any tests or help because she thought that I was a drug seeker, when I specifically told her I did NOT want to be prescribed any narcotics. Grr