What Causes Pain In Lower Back Radiating Towards Hips And Knees?

For the past 2 wks, I have had pain in my lower back, going into my hips and the to my knees. No pain between my hips to my knees, but my knees give out on me. My breasts are VERY tender to touch. My doctor has diagnosed me with Costochonditis, but after researching on the internet, I don t think this is the correct diagnosis.(sp) He is very narrow minded and does not like to be overruled. It took 9 mths for him to send me to a ortho when I had tore my rotator cuff and had to have surgery. He put me through so many unnecessary tests and I kept telling him it was my shoulder. I finally got so irritated with him that he referred me to an ortho just to shut me up. Needless to say, I am looking for a new GP. Does this sound like an ortho problem, neuro, or what?? Need serious opinion. Karen