My baby is the same he is 4 and half months old they call it reflux. I am currently breastfeeding and the doctor advised to give him baby gaviscon which comes in sachet. As you are feeding your baby formula you just add sachet to the bottle which is easier and makes a lin8ng after feed so the they dont vomit. as i am just breastfeeding him i don't have time to give it to him with syringe as he has already vomited before i even give it to him.

Try Emfamil AR formula (if formula feeding), we had the same issue, switched to the AR formula and immediately fixed the issue.