I have a 5 1/2 month old barred plymouth rock hen, unsure of weight, but she has been steadily growing, although slowing down now. She is beginning to lay. Some eggs are still very soft, some are normal. The past couple of days she has been lethargic, eating less but seems thirsty. She also has watery diarrhea. The diarrhea is somewhat clear with some white. Also, her throat/chest area appear distended/slightly bulging outward. She is usually very active and talkative. She is now quiet and not moving around much. She does hop up onto roosts in the chicken run and walks around a little bit. Her gait appears normal, but slow. Her diet has been Start N Grow chick feed, Scratch Grains, some added grit and oyster shell calcium. She also eats lots of veggies, usually broccoli or corn, but some green beans, tomatoes, lettuce and lots of weeds from the veggie garden. Just started mixing in Layena pellets with the Scratch Grains. She lives in a chicken run enclosed by chain link fencing, dirt floor during the day, and at night she goes into the enclosed coop, although we've been leaving the chick door open at night. There is a heat lamp on at night. She sleeps on a shelf or on the roost. The whole coop has pine shavings covering the shelf, floor. The shavings are swept out everyday and the shelf and roost, and window sills are disinfected with Lysol wipes almost everyday. The nesting boxes are filled with straw. The feeder and waterer in the coop are suspended to avoid stuff getting into them, but they get a few bits of shavings anyway. The water is changed about every 3 days. The other chicks include another 5 1/2 mo. barred plymouth rock hen, 5 1/2 mo. old Orpington rooster, and two 4 1/2-5 month old Orpington hens. Everyone else seems healthy. Does this sound like anything specific to anyone? And what should I do? I don't want to over-react if this is a common, passing ailment. However, I do want to be an informed, responsible chicken owner. Thanks!