My brother aged 65 years has undergone knee operation two months back. Now he is freely walking and there is no problem related to knee. But for the last 20 days he is regularly getting temperature 99-100 every day for a limited time say 1 hour. After taking paracetamol he becomes OK. He has consulted a doctor and he suspected TB. After making tests doctor confirmed that he has no TB. He is still suffering from fever every day for a limited time. Pl advise.