White, Mucousy Poop in 4-week old chick???

Has anyone ever had a chick who had white, stringy poop that looked mucousy and that seemed to go back up inside the chick after it pooped? At first I thought the chick's innards were coming out.. I've seen him poop this way twice. Not sure whether he does it everytime or not. What could it be? It is not bloody. The chick is 4 weeks old. Could it be from the stress of being separated from his Stepmama? He came to me a week ago with 2 of his siblings. A third had been killed by a dog, and another stayed with his Peahen stepmama. He's half Barred Rock and half Ameracauna splash. All comments will be appreciated.