He may be suffering from a certain infection or a gastric issue.
Give him syrup. Domperidone and then feed after half an hour of the medicine.
If it still persists, kindly consult a paediatrician as soon as possible and don't delay.
Hope your child gets well soon.
If vomits are frequent, child has avulsion to feeds specially liquid , and developed frequent chest infection as well and doesn't get better completely with antiemetics like domoeridone then parents shall consult specialist 2 condition in the age group mentioned by you are : reflux disease and pyloric Stenosis . out of which second one needs an ultrasound of abdomen. So it would advisable to meet Pediatric gastroenterology specialist and get these 2 factors ruled out. Hope child gets well soon. Regards