Hello, I have experienced sudden onset of pain this week on the left side of right knee. It becomes rather severe at night and is so very sore in the daytime. I do not recall anything I did to injure it. It causes me to limp or walk very slowly. It is sore to the touch. What kind of doctor do I need to see. I don't expect miraculous cures but would like to know what might be causing the pain. So I can deal with it appropriately. I am a 69 yr old female .