If it's formula, I would consider changing the brand. He may have a sensitive tummy. Remember to burp him after every feeding and have a burp rag handy.. Some babies just spit up a lot. If you're breastfeeding you could have something in your milk upsetting him, a lot of nursing moms have to give up dairy.

maybe he has severe acid reflux?

@batula143, it could be a milk allergy or reflux

He could just be over eating my son did the same thing, try only giving an oz at a time if BF pump and monitor how much you give him