5 month old sleep habits

This is my second child and like they say every child is different and sure is in my case . My first son would sleep the night as a baby and was a very quiet kid at that but now my second son is just starting to sleep a lil more but he stil has 3 botlles at night . One at 2am and one At 4am and one by 630 in the morning . Pediatrician recommended a little cereal in the bottle but that dont work !! I tried feeding him dinner before bed and he will poop in the middle of the night to thw point its all in his back and i have to change his clothes entirely and it never fails! What do you guys suggest i do to help him sleep the entire night ??