He needs to poop
From Create Your Own Story
The sound of suckling. The sound that echoed in the hall was the suckling of the babies (Kids dammit! Some of them were as old, if not older then I am!!!), with grunts and the crinkling of diapers a chorus to it. He moaned as the nun rubbed his back. Her skin was like a soft, fresh silk and smelled like violets and baby oil.
Daniel's tranquility was suddenly shattered when he felt his body cringed. His abdomen cramped, possibly in reaction to the nun's milk. His stomach is churning, and before he knows it, he loses all control and relieves himself into his diaper. He gasps in shock, poop flowing into the seat of his diaper against his will. He even pees a little too. He places his arm under his butt, feeling the warm load grow beyond the plastic in a desperate attempt for it to stop, trying to pry himself away from the nun's breast.
Daniel never felt less in-control, and started to sniffle in his feeding. He felt his hunger die completely, his lips finally detached from the tit as he started to cry, bringing his hands up to his face to catch the tears. The nun calmly placed her hand on Daniel's chest, pushing him on his back, smearing the mess in his diaper across his butt. He turned his head, seeing his milk-sibling lie back calmly as the nun unclipped the black-haired boy's blue onsie, changing his wet diaper. As soon as she clipped the boy's onsie closed, freshly changed, she placed a pacifier into the boy's mouth as the boy calmly sucked on it, content.
The nun then moved to the crying boy, reaching under the bed, grabbing a fresh diaper as a trashcan rose from the floor next to them. She calmly undid the tapes of his diaper. Daniel stopped sobbing, astonished. He tried removing the infantile garment earlier, but it refused to come off as if it permanently bonded to his body.
She lifted his legs up, wiping his lower half down with cold baby wipes as she placed a fresh, identical diaper under his as she laid him back down, throwing the soiled diaper into the trashcan before it melted back into the ground. She taped him back up, taking a pacifier from the inside of her robe and placing it in his mouth. He started to suck on the pacifier, compelled into the action like before.