Hi there ~
I understand your concern for your baby boy. I also believe that there is a catch up phase where you cannot count 5 weeks towards the regular milestones as your boy was premature. I think it is normal to have these kinds of bowel changes during your changing or weaning him off of the regular foods and introducing new foods. I hope this helps relieve your anxiety
. However if things go bad a visit with a pediatrician
should be in place.
Take care and have a lovely day!