Girls, I need your advice ?? My youngest son is sick, he has a strong …

Girls, I need your advice ?? My youngest son is sick, he has a strong cough and there's some wheezing (( they prescribed injections, as well as syrup Prospan, so I gave him syrup in the afternoon, he started vomiting, he can't swallow the syrup, he holds his breath and then coughs, mucus comes out at that moment with the syrup, such a story in the evening, I don't know what to do, but syrup needs to be taken... Before that, I remember I gave him Hippolyte Forte and Bifidobacterium, the same reaction with vomiting, I stopped giving it. Has anyone had this? Suggest how to give the child syrup so that there is no vomiting