My mother is 54 year old lady with high fever with chills for last 10 days. All investigations are negative except that urine had bacteria and pus cells 12 to 14. She was given course of nitrofurantoin. The fever did not subside. Sgw also developed cough dry in nature. She was given azithromycin but no relief. She was started on cefixime and today is day 8. Her repeat investigations including blood culture and urine culture is negative. She also developed pain in left wrist followed by pain in both knees. She took diclofenac for same and joint pain subsided. She is still having 103 degree fever and today is day 13 of such fever. Her chest xray also was normal. I am baffled. She once had an episode of arthritis 16 years back which was RA negative and not labelled anything specific. What should I do next? Please advise.