One of my week old chicks came down with pasty butt. I washed the area as clean as I could, but she seems to have diaper rash. What causes this? The other 29 chicks seem fine. What else can I do for her? Iʻm sorry to say that my Dadʻs response would be "Some chicks just wonʻt make it", but I hate to take that as an answer. Help!