I had a Dominique chick in my bunch that was not growing as quickly as the others. For a bit, she seemed to be getting pushed out of feed and water, as well. I isolated her with her own feed and water for about a week, and then put her back with the others when she gained some strength. She not only did well, but was one of the feistiest of the bunch. She never got the same size and was always smaller than the others, but she thrived and did well. I guess what I'm saying is that as long as she is eating, drinking, pooping and not getting picked on or seems sickly, let her go. She may surprise you yet.