Cough

My daughter has been coughing for over three weeks now and I am starting to get a little worried. We went to see her physician a couple of weeks ago and got a sample medicine and it does'nt seem to help her cough to get better. I've been giving her some pediatric cough syrup as well with the right dosage, but doesn't seem to work either. Next week I have to see her physician again for the follow-up visit and hopefully he/she can give her the right medicine that will finally work on my daughter's cough.