In the last pic, one looks a bit fluffed up. I would be a bit worried about her. Lethargy, hunched posture or puffing up, not eating, runny poops that may or may not have blood, and ruffled feathers can be signs of coccidiosis. Chickens get coccidiosis from the soil and their poops, and as they grow up, they usually develop resistance between 11 and 20 weeks of age. I would leave them all together, and treat them all with Corid. It costs about $19.