Cough persist for long time. Reside.

Hi, my kid 4 years weight 19kg old got cold 2 Weeks back . He had runny nose and slight sneeze and and cough.. doctor gave delcon and levolin but the symptoms didn't reside.. he got coughs at night as well.. so along with above my doctor gave lasma 4 tablet,  Azithromycin and cofstop A. Even after having azi for 3 days the symptoms didn't go and yesterday he told to stop azi and gave mankind cv. But even after having all these he is severely coughing for half an hour at night.. I'm so scared.. he is having delcon.cofstop A, levolin, lasma 4 and mankind cv.. I feel like he is giving so much drugs but still the symptoms of cough is not getting reduced.. Kindly advice if the treatment is going in the way or what can be done further. I'm worried about the continuous cough that elevates during night.