We have incubated/raised our own eggs for about 3 years now. We are on our third generation of chicks and they are about 3 months old (or about half grown). We've never before had an issue with illnesses or anything like that but all of a sudden in the past four days, we've lost 4 chickens (1 per day). The first one was pecked by the big chickens to death, so we separated the big and little chickens, as we combined them too early. But then others started dying and we cannot tell what's wrong. They look normal, but they act really weak. They have a hard time standing/walking, but they do drink and eat a little. We went to our local feed store and bought Duramycin-10 Tetracycline Soluble Powder and put that in their water and then we bought medicated chick starter/grower. We also got a treat/nutrient block just for good measure. Is there anything else we can do to stop this? There is one chicken we caught before it died and it currently has white feces around it's vent and is acting really weak. They are like pets to us and we really care about them. Any answers are appreciated, and thank you for reading and helping!!!!