My 5 week old little girl does this and I spoke to the gp today about it and they said it’s normal for babies to do it
It’s perfectly normal for babies to do this, although it can seem alarming sometimes. If he’s gaining weight and only does it occasionally I wouldn’t stress
I don't know if you are bottlefeeding but in case it helps, my gp said to give 1oz/30ml at a time and then pause to burp, as this can reduce the issue of throwing up.
If it’s only twice I wouldn’t be too concerned. Newborns can posset after feeds sometimes. If it becomes regular speak to a gp. We are currently trying out me having a dairy free diet as I’m breastfeeding and think baby has cmpa. Gp has given us baby gaviscon but holding off giving it as I don’t want to replace the sickness with constipation