<s>[INST] For a week , I ve had low grade fever and extreme pain in my right tail and lower back. I had applied heat and it still hurts. The pain wakes me up around 4 in the morning and is in bearable. I had x rays of my lower back it show bone spurs. I also need knee replacement of my right knee. The pain is on my right side. What can this be? [/INST] Sir I understand your concern but without physical examination and investigation it gets difficult for us to advice you anything. Low grade fever can be due to tuberculosis and if the bone is getting involved or something can pain. But we can't just randomly tell you diagnosis without detailed examination and investigation to rule out few conditions along with malignancy. Do you have weight loss? kindly give us detailed history and investigation attachments. You can put direct query to me. Hit thanks if you like my advice happy health! </s>