I have 2 3 month old chicks, buff Orpington mixes that just are not thriving. They are weak, they’re always fluffed up, really unstable on their feet, bad balance and seem to have weak legs as they run to the food, but just sit down when they get there. They are in a small coop with 7 older chickens(not laying yet), they all come from the same place and have been together since hatching. I have pine animal shavings for bedding, have been fermenting feed, but they just seem to be getting worse. Any ideas?