My mum age 74 had a single TKR 60 days ago. 10 days after surgey she develped high fever ajnd chills. On 16th day after surgery a debridement was performed. Cultures did not grow. She was on an intravenous broad spectrum antibiotic -zobactim for 2 weeks in hospital followed by 21 days of oral antibiotics. 3 days after this course was completed she started getting a low grade fever of 99.7 max. 12 hourly cyle that responds to paracetemol or goes away on its own. UTI was detected andis being treated. She is now on her 4th day of antibiotics for the UTI and urine culture shows only mild level of pus cells. She feels completely debilitated and ill (flu-ish) Knee has healed completely. Only marginal swelling and redness but still warm to the touch compared to the unoperated knee. Low grade fever and debility is persisting. What should we be worried about and what should be our next course of action.