I recently got into chickens on our small farm. I bought 4 silkies, just for pets, 5 cochins, 9 lavendar ameracaunas, 4 black copper marans, 5 buff orpingtons, and 3 more ameracaunas from four different sources. All of them have done great except the lavendar ameracaunas bought from a single source. Within three weeks, 6 of the 9 of them have died. Should I be suspicious of the source where I bought them, or is it more likely that I'm just doing something wrong? Why only those ones, when the others all seem very healthy and happy?