Can a baby at 4 months become lactose intolerant? My baby use to eat 5oz every 3 hours and did really good. Now he is back to 2 to 3oz every 2 hours besides his long nap and at night. He is spitting up a lot after his feedings. His poop is back to really runny and stinks like no other. He is crabby and cries in his sleep. He farts like crazy. When he is sleeping he is really restless. I already have my little man on spit-up formula and has been for months.