Talk to Gastroenterologist on Vomiting Nd Motion During Cough Nd Flu

Assalamualaikum! My baby is 20 months old. Sinc last month he had a flu nd cough, drs already given him antibiotics. But after few days he again had cough nf flu. We again gave him antiallergy nd cough syrup. But now from last 3 days he had started coughing too much nd then he had flu again also, mgr ab ye vomit or motion bi kr raha hai from last 3 days. His dr gave him only antiallergy syrup now . Mgr iske motion or vomit ni ruk rai. Vomit me ek white curd like subtance nikal raha hai. Jo ke samjh ni araha hai ke ye kya hai. Please help me out. I'm too much worried. Please tell me what's the reason of white substance in his vomit and what should i do now?