Maybe it's gas? You'd be surprised how much a baby can cry when they're full of trapped gas. My first dd acted like that during/after feedings. We had xrays done and her tummy was full of bubbles. We tried everything, burping often, gas drops, changing nipples on the bottle. She was formula fed so we switched formulas and that did the trick.
My ds is bf and does it sometimes but not that bad. Mycelon drops are enough to help him. I can rarely get a burp out of him after he nurses but he toots a lot. Sometimes he'll start grunting and crying, we give him some of the gas drops and soon after he starts tooting and calms down.