Hi mommy. Has the baby been burped properly? You may try burping the baby. It may be that the baby has colic. You may try massaging the tummy gently in circular motion. Or try moving the baby's legs like riding a bike. Then push the legs gently up to the tummy to put pressure on the stomach and loosen up the way down the baby's but for a fart.
Is your baby a boy? if boy they tend to feed more. my boy is 4 weeks and drinking 4oz every 3 hrs.