my boy used to has that also, so bloated up to his chest area. He's also bf and latch on, no bottles at all. pediatrician unable to explain the reason and insert pill into his anus, letting him to give out all the air. But be prepare that there will be lots of poos coming with it also.
After that, he's given the rid wind medicine and reutefene drops. Even though i latch on, i was told to burp him every feed. It's a must, not a choice. So baby managed to burp most of the time. Also was advised to introduce pacifier to prevent baby from crying.
Did all the above and my boy gets better, no more big tummy.