S.S.
I would put him on baby probiotics and get healthy flora into his gut. Maybe change formulas to a lactose free and stop interfering with his bum by sticking something in it. You are loosening up those muscles. Not a good thing for him to rely on you to do his business. This is a system that should happen automatically. Give prune juice everyday/diluted. Keep him on his tummy as many as 4 times a day for 30 minutes each time to build core strength and abdominal muscles. Movement is the best thing to build that right brain which takes care of automatic functions like breathing-pooping.