I have 7 pullets around 8 weeks old now, I noticed one of them started to refuse to eat feed now and has became visibly smaller than the other ones. She will still eat dry meal worms and also grain feed that we leave in the coop, drinks water no problem. She also free range during the day when we let them out, but the other ones we did not notice them just out right refusing to eat the feed when they can. This is the same feed they had since they were chicks, anything to be concerned off?