Just realized I didn't respond to everything in your post!
What are they fed: organic layer crumbles
Are they wormed: no
Has there been any diarrhea: Some is runny, clear and white. But there is still good firm stool as well.
Other symptoms to give some clue to the problem: It starts with the...
I'm in Oregon. It's too late to do a necropsy, we lost just after my post and she's in the ground :( I'll keep that in mind for next time (hopefully never!!) But I'm fairly sure that one of my older girls is getting sick.
Help! 4 months ago, we hatched 2 eggs with a broody hen and everything seemed great. One of the chicks stopped growing at about 10 weeks, had a hunched in look with her head drawn into her shoulders. She died.
Then, a member of my original flock had that same posture, hunched in on herself...