I am worried about my hen who is 16 months old. She had been broody about a month ago, so I built her a run so she wouldn't go under the house and hide. She's been confined in the run for a month, so I would think she'd be over her broodiness and she is laying eggs daily. Her legs have become less orange. Recently I have noticed a change in her comb. The back tips of it have gone a grayish/black, and the part right over her beak is blackish, too. Another hen had her comb go grayish black and I assumed the worst, but she had rubbed up against something under a car, and the grayishness was only on one side. The current hen in question has grayishness/blackness on both sides, and I can't see anything in the run she could have rubbed up on to make it go this color. Also, she's pecking out a lot of breast feathers, which I know is a sign of broodiness in a hen, and I thought that was why, but now I'm wondering whether this could indicate some other problem? She has a good appetite. I would say it's almost too good. Today I saw her eat a thistle, and I didn't think chickens like thistles? I feed her arugula, but I wonder whether she thinks she's not getting enough greens in the run, after having been a free-range chicken for so long? Could she have eaten something poisonous? She sticks her neck out the run to reach whatever green is handy, and I'm wondering whether some of them could be bad for her. I think I have seen her eat wild morning glory vine and blossoms. I have fed her spinach out of her raised bed garden box, but I'm a little leery of spinach because of the oxalate intake. I don't see signs of mites, though she does preen a lot. I also see her gape now and then. So I wondered about gapeworm. But I don't like to treat for stuff without knowing for sure what the problem is. I wonder whether it could be fatty liver disease? I don't feed my chickens scratch anymore. She ate a tiny piece of plastic sheeting about a week ago, maybe the size of a dime, quite weathered and thin. I wondered whether that could have made her sick. Her energy seems good. Last night she tried to fly out of the run. She didn't succeed, but she had fun trying. It's the blackened comb that really worries me the most. Now I'm wondering whether it could be parasites. Her sister doesn't peck her breast feathers out. She's never been broody, unlike this one. And her comb seems okay, with maybe some grayishness from dirt from dust baths, but not nearly as dark as her sister's comb. What do you think is the likeliest disease my chicken might have, based on your own experience? I wonder whether I should get some Sevin and start with that? I live in Salt Lake City, Utah. Thanks for your help.