Help - What's wrong with my Black Copper Maran

Hi all! This is my first post here but I've been following since we inherited our flock of 26 hens in October. One of our BCMs appears sick. Suddenly her comb and wattle have gone very pale. She is also moving very slowly and isn't at all fearful. I can rush up to her and she barely flinches. She tries to follow the other girls around (we free range) but keeps getting left behind. I do see her pecking at the ground and she is eating little bits for sure. She has a messy rear. Looks like runny droppings for sure. I followed her to check her droppings, and was able to bag a tiny bit. Green and a bit runny. I'll attach a picture of her with another hen so you can really see the difference in comb color. Anyone know what could be wrong with her?

Welcome to BYC. Do you know how old she is? What do you feed your chickens? I would look her over for signs of mites and lice. Some mites only come on the chickens at night, so checking at nighttime with a flashlight may be necessary. Mites can cause anemia. You may want to get some Poultry Cell or NutraDrench, and give her 3 ml orally each day. That has vitamins, minerals including iron, electrolytes, and amino acids. Encourage her to drink and eat, and making a very watery mash of layer feed with water, and a tablespoonful of plain unsweetened yogurt may get her eating. The probiotic yogurt can help diarrhea. Chopped egg and canned tuna are other foods that may appeal to her. It is hard to tell what is wrong with them without ruling out other things. If you could collect a few of her fresh droppings, and take them to your regular vet for a fecal test, they tell you if she has worms or coccidiosis. Feel of her crop to see if it is empty, full, soft, firm, or puffy. Some hens 2 and older can develop reproductive disorders such as internal laying and egg yolk peritonitis, which can cause some of the same symptoms. Below are some articles to read about internal laying and egg yolk peritonitis and the last one is about what to look for in lice or mites:
http://scoopfromthecoop.nutrenaworld.com/tag/laying-issues/
http://www.theveterinaryexpert.com/backyard-poultry/egg-yolk-peritonitis/
http://anrcatalog.ucanr.edu/pdf/8162.pdf

Thank you! I'm not sure exactly how old she is because we inherited them all. I think some of them are about two and the rest are one yr old. I think she's in the older bunch for sure. We did give her Nutri-Dench this morning and I told my husband to pick up some yogurt. They eat New Country Organics Corn Free Layer Feed. I didn't know about the night-mites! I'll check tonight at headcount and see if there are any creepers on her. I'm going to head out in a bit and follow her around to see if I can get some more of her droppings. The bit I got before was so tiny I'm not even sure our vet could do anything with it. Is there any way to check for the reproductive disorders here? Or would that require a trip to the vet?

Every vet is not good at diagnosing internal laying or egg yolk peritonitis. Most times it is diagnosed after death with a necropsy. The symptoms are different in hens, but they describe common ones in the articles I posted. If you can confine her to a dog crate with a puppy pad, old towel, or paper towel, you could collect some droppings overnight, and then release her. I am not an expert on EYP, but there are a lot of threads here on BYC if you do a search at the top of this page. Many turn to antibiotics, but there is no cure for it.