1-2 days ago, I noticed one of my RIR 2.5 yr old hens was moving a bit more slowly than usual. Still doing the normal chicken activities, but in slower fashion. She's been eating, but not with excitement, and she put herself to bed a bit earlier last night. This morning she came out with the other girls, but glanced at the feed and walked slowly past it to be alone (not hiding though). What I also noticed this morning is that she, from time to time, will pull her head and tilt it. She's not really "jerking" it, but pulling it sideways. I did NOT notice her gaping her mouth any. Her stand and feathers are beautiful - I don't suspect parasites. Any ideas? Sour crop? Thanks!