For the last 15 days, my father has been suffering from fevers (100 or sometimes a little high) at night, body pains, physical pain at the back of his throat near his shoulders and a little weakness. We all thought it to be a normal fever because of the cold weather and work condition. However later He did a blood test, where everything was normal. No signs of malaria or thyroid was normal too. The doctor has prescribed him leon 500 mg tablet for 5 days . But his condition remains the same. Can it be influenza? Is yes, what are the tests for influenza? Please help us out