Talk to Pediatrician on Pediatrics

my five month old son drinks milk only during sleep...when he was three months old he was crying at the time of feeding and whenever he comes in feeding position he starts crying and slowly he develops sleep feeding from the last two months..the main problem with sleep feeding is that he experiencd hard coughing during feeding and ejects all the milk (vomit). i never forced him in feeding time..but i dont know what i do now