Son has bad cough with A strain Flu?

14 year old son has tamiflu for the swine flu (diagnosed 4 days ago) and is doing better fever wise, but he has developed a very deep chest cough with lots of phlegm, what is the best thing to give him? does this cough require a recheck by doctors? Should I keep him out of school still even though he does not have a fever for 2 days due to the cough?