I have 8 chicks that are a week old today ( 2 Blue Orpingtons 4 Buff Orpingtons and 2 Golden Comets). I got them from Meyer Hatchery, they were not shipped I live near by and picked them up myself. Well one of them (Peanut, a BO) keeps getting pasty butt! She is the only one that is having this problem. She also seems to be smaller and less developed than the other chicks, the other ones wing feathers are coming in and some tail feathers too, but Peanut's feathers are coming in much slower, she barely has any wing feathers. She's not lethargic, I think she's eating and drinking fine and runs around the brooder with her sisters. I have started feeding them yogurt with active cultures once a day (just started yesterday). I have heard unfiltered acv in the water works too but can't seem to find it in the stores. How long will it take for the yogurt to help her and is there anything else I can do to help her? Just want all my chickies to be happy and healthy, help! please!