Cough

My son has a cold for about a week now, he first got it for me then his father unfortunately. I took him to the doctor and he prescribed him antibiotics syrup and neb treatment. My concern is he coughs here and there for about a full minute then sounds like he is struggling to stop then he feels the pain of coughing and start holding it it or push his body down as he coughs more. I was wondering if similar formula that he has been using for the past 11 months of his age is causing problems? Any similar experience? Or ideas?