Spitting after each feed due to gastroesophageal reflux which is common in infants and usually it subsides as the age increases mostly by 6 months of age. Do burping after each feed and give frequent small quantity feeds and if still persisting you can give prokinetic medication like domperidone
after consulting your Pediatrician
. You can give exclusive breastfeeds to your baby till 6 months of age and there after in addition to breastfeeding
you can start complimentary feeding.