The Cough That Won't Go Away

Maddy has had a persistent cough for the past 2 weeks and according to his doctor, he has a "90 day flu". Now I don't know about you but I don't want my child to have a flu for 3 months. The medicine that he has prescribed doesn't seem to work and in the cough and flu have robbed Madison of his appetitie. He's lost a lot of weight. I've been reading through information on the Internet and most data suggests that cough medicine doesn't work on children, perhaps even making the cough worse. Who do I trust?