Hello sir/ma'am! My father got covid after staying 10 days to hospital, discharged from hospital 20 days ago.From yesterday,he has a fever around 100 C which persists for a short time. When paracetamol is uesd fever goes out, after few hours (7/8 hrs) it reocurrs. He has a little stain in left lung due to previous cov, which will slowly goes off according to doctors. What might be the reason for fever? Is any test need to be done?