My baby has been having very liquid bowel movements since changing his milk. Is this normal?

Yes, it is normal for a baby to have loose stools after a change in formula. As long as the baby is still wetting and dirtying their diaper, gaining weight, and not showing other concerning symptoms like fever or vomiting, there is usually no need to worry. It can take some time for a baby to adjust to a new formula, so patience is key. There are also some tips for reducing spit-up frequency, such as using a smaller nipple size, burping the baby frequently, and giving smaller amounts more often. If you have any further questions or concerns, it's always best to consult with a healthcare professional.