Low grade fever for 4 days

How long does viral fever last in baby less than 6m? He’s attending ifc and suspect he got it from there cause its so random he suddenly got fever. 4 days and he’s still having on off low grade fever. We do give him paracetamol only when the fever shoots up like almost 38, other than that we just put fever patch and give him a bath Still active, drinking well, nap & sleep.