Don't Understand At All

Ok so I had these xrays of my knee, shoulder, and lower back. The guy that took them said they would be at my doctors office on the 9th of february. I waited for a call from the rhuemy with what was going on with the xrays. Nothing happened so finally I called to see what was going on a week later. A nurse called me back as was told did not have the xray infor as of yet would have to call and get the report faxed to them. She called me back and said everything was normal. I then get a call from my gp office about the xrays and the nurse said that the pain was arthritis and that they could add a pain pill if I wanted. When I told her that the rhuemy said the xrays were normal she did not know what to say to me. She put me on hold and the doctor came on and said if they got the same report as she did there is arthritis throughout my shoulder, knee, and into my lower back. There is a notable size bone spur in the knee. She said this is the reason for the pain and if I need something stronger than the ultram she could add something. I told her the rhuemy already had done that I think. How can 2 doctors get the same report and have different findings? I just don't understand this at all. Would love to hear a reason for this if any of you have one.