What Causes Severe Cold And Vomiting Inspite Of Giving Levolin Syrup?

Hi Doctor, my son is 9 months & 3 weeks old. he has been having cold for nearly a fornight. he had prescribed sinarest with paracetamol (0.6ml) thrice for 5 days and he seemed to be doing well. But we had to travel with kids who had severe cold and later the baby s cold worsened and so he was prescribed levolin syrup (1.5ml) twice for 3 days. he was also given nasiviion saline drops thrice (1 drop in each nostril). He has started vomiting since yesterday. Kindly advice what we should do.