We’ve just had our boys tongue tie revised and sick can be due to air as a result of tongue tie. Do you know if this has been checked? :)
My baby has had it from the beginning. Sometimes more sometimes less. Sometimes he doesn't burp at all. Try to hold him kind of in a sitting position 15 mins or longer after feed. So don't put him to lie flat after eating straight away. For us it helped though he sometimes still have those accidents but less than before. Good luck
Try winding every time you stop, not just at the end. Makes the difference with mine.
Could be worth seeing the GP, my first baby had silent reflux and we got baby gaviscon x