Our barred rock, Ricki, is about 2 1/2 years old. She's normally bouncing around, bullying the other girls and just generally a happy chicken. Before her recent molt, she seemed sick on a number of days. She was very lethargic, even falling asleep while standing in the middle of the driveway. She also seemed like she had some congestion in her beak (kind of gurgle-y). She did not lay an egg for 2 weeks or so and we were very concerned. At first we thought she might be eggbound but then she started having gooey, shell-less eggs just fall out of her. Some days she was absolutely fine then the next day she seemed ill. There was often a mucus-poop combinanation discharging from her vent. Then she molted and the pressure was taken off her to lay. She went back to being energetic (with no discharge). Now she's done with the molt and the shell-less eggs have started again, along with her appearing sick. She has full-time access to oyster shell and layer mash so it seems odd that it would be just a calcium deficiency. Also, she gets out for at least an hour of free-ranging every day, and some days stays outside from dawn till dusk. Her 4 coop-mates are all fine. It's just her. Anyone have any idea what may be causing this? Is she prone to something?