I have some biddies about a month old that are starting to puff up andd look sick. They kind of level out as the day goes. They are free range. They feel thin. Poop is brown and runny. Not what i would call bloody. Tractor supply guy told me to do oxytetracycline instead of corrid. Since my adult chickens aren't dying sporadically. But ive lost a few chicks. Would both hurt to do on the entire yard?