Uh, take the child to a real doctor and stop gambling with his health. Modern medicine seems to work pretty well, the last I heard.
Going to the doctor over a cold/cough is the reason why people have to wait hours to see a doctor when they go in with more serious ailments.
IMO, people need to toughen up and stop relying on modern medicine to treat passing, minor ailments. A cold takes about two to four weeks to pass, they have always taken 2-4 weeks to pass and in our lifetime will probably continue to take 14-30 days to pass no matter what the doctor tells you or how much the magical pills cost.
By the way Shangrila, did you try the Jagermeister? Has there been any improvement?