My 4 month old is constipated & in pain . What did you do????

So since she’s been born sometimes she would go 3-4 days without pooping. But then when she turned like 2 and a half months old she started going once a day or once every other day and her gas got a lot better. I’ve always suspected she has colic but the dr has never said that. I have told them about how bad her gas is and the screaming that doesn’t stop for like an hour or two sometimes until she farts a bunch and falls asleep. Wel now she’s 4 months and the past like 2 weeks will go 4-5 days without pooping. I’m& by the end of those days is in a lot of pain. Screaming again and nothing I do makes her feel better until it just goes away on its own. They told me to try an ounce of prune juice. So I did last night and she spit all of it up. And still hasn’t gone. I think it’s the 3rd or 4th day.