I have an Australorp, about 6 years old. For about the past 24 hours, she's had this odd posture. She seems reluctant to move around a whole lot, but is still moving, and seems possibly interested in food. She's got dirty feathers around her vent, and this has been a somewhat ongoing issue. Her third eyelid closes often like she's in pain or discomfort (obvious also from her posture). She's part of a flock of 5; all others seem healthy. Any suggestions?