Patient underwent dj stenting one month ago, now 10 days ago stent removal was there. After that he underwent septicaemic shock, now safe from critical condition.but fever is still persisting in a regular interval, tlc is decreaing trend.he is currentli iv meropenem and ofloxacin.usg is resolving pyelonephritis. All cultures are negative. What canbe cause of fever, and what should be next line of managemnet.