I have six pullets who are 4 months old. One of them reeks of chicken poo when I hold her. Her vent looks normal and her butt fluff is clean. The rest of my girls smell fine. I've also noticed she isn't growing as much as my other girls. She acts fine and eats and drinks normally. She does tend to keep to herself, but I've never seen her being picked on. Maybe they don't want her close since she stinks Haha, but really, is this normal? What could be causing it?