I have 4 week old chickens. They have been doing great and growing and eating well. I have noticed dark runny poop in the coop but they seemed fine and healthy. Today one or two of my chickens look lethargic. One is very lethargic and sleepy when she is usually one of the most energetic, loud and hardest to catch. Something seems very wrong. The other chick seems lethargic but not as sleep/drowsy as the other one. What could this be? What should I do? I have 4 other chick in addition to these and they seem normal. I have been feeding starter grower mixed with some grit. Fresh water daily. They were on cedar bedding (non aromatic) and I have switched to pine thrown over the top. I have not given them any treats or other food. The poop does look very runny and black but that has been for at least 2 weeks and they were fine. They lethargy is scary. This chicken let me hold her on her back and she kept her eyes closed and didn't move. that is NOT normal. She is one of the loudest and wildest of the bunch normal. she should be flapping her wings like crazy if I try to hold her that way. Something is wrong. please help!