One of our baby chicks chirps loudly and cries when ever she takes a poop. She doesn't have pasty butt, we've given her probiotics in her water, and they have sand/grit available. They are all about 3 weeks old now and she's been having trouble pooping since week one. The rest of the flock has no pain or problems when pooping and there poop doesn't seem as hard as the one who cries in pain. We can't figure out what to do to help her, any ideals??