Re: Mystery Gas/Colic/Pain in my 5-month-old
Welcome to the forum!
What you describe sounds a lot like a forceful letdown issue. Baby is pulling off and fussing while nursing, baby has gained weight very well, baby is feeding rapidly, she may be clamping down on the nipple (compression of the nipple will slow milk flow), she's gassy, and you are still frequently feeling full at 5 months postpartum (by 5 months, most moms have a milk supply which is closely matched to their babies' needs, which means that they rarely if ever feel full). Those are all classic signs of oversupply/forceful letdown.
When the baby pulls off the breast while nursing, what do you see? Is milk streaming/squirting from the breast?
The first thing I would do in your shoes is to move back to on-demand feeding. When a baby is struggling with a forceful letdown, smaller, more frequent feedings tend to improve the baby's experience, because the breast doesn't get quite as full in between feedings and that usually makes letdowns a little more tolerable. The second thing I would do is to try reclining while feeding. Reclined nursing positions enlist gravity to slow the milk flow to the baby, which can result in a more comfortable nursing experience.
Once you've done those two things, I would give it a few days, maybe a week, and see if things improve. If they don't, then you may want to move to something called block feeding, which is feeding on only one breast per feeding or for more than one feeding in a row. Block feeding leads to reduced supply, because when milk sits unused in the unused breast, the body reads that cue as reduced demand and throttles back on production. Please do NOT block feed if you are scheduling feedings- there's a chance that you could end up with supply which is too low and a baby who is not getting enough chances to nurse and not enough milk to continue growing.
Managing milk supply through block feeding is more and art than a science. Because supply fluctuates from day to day and over the course of the day, some moms will need to block feed on some days and not others, and many will need to block feed only part of the day (usually during the mornings, when supply tends to be most abundant).
Finally, on to the gassiness. If oversupply is causing the gas, managing the oversupply should help your baby feel a little more comfortable. But crying in response to gas in an otherwise healthy baby... That's probably not a health issue. It sounds more like a personality issue. Some babies are mellow about their burps/farts/poops, and some are not. The ones who aren't are the ones who let you know every time they pass gas, by looking distressed and crying.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"