Thank you for your query,
Children usually vomit after cough and it is called posttussive vomiting. And it is not a true vomiting and not cosidered as his unliking of syrup.
You can take mucolytic
drops like mucolite or kufril drops after your Pediatrician
advise instead of ascoril-ls.
Continue sachets for loose motions and give sips of Pedialyte
to prevent dehydration
Hope I have answered your query.