This morning I noticed one of my girls has a very pale comb compared to the others. They are all about 5 months old. She is also not as active as the rest. I separated her so I could keep an eye on her eating, drinking, and pooping. She's not pooping much. Sometimes she looks like she's going to poop but nothing comes out. When she does it looks pretty normal. She's eating and drinking some, but still not as much as the others. I gave her some scraps and she ate those pretty quickly. We changed their food over to laying feed about a week ago. She's chattering a good bit, especially when I go out to check on her. I checked for lice and mites on her and the others but didn't find anything. Is this normal? If not, what should I do? What could it be?