I have an almost 4-yr old RIR hen who has been "off" this week. She seems hungry, but isn't eating. She'll walk up to the food bowl, pick up a piece, and then let it drop out of her beak without eating. She's done this with her favorite treats- corn kernels and mealworms- as well as regular pellets. She is excited to eat lettuce/kale treats. I've seen her drink quite a bit. She also seems very eager to add grit- she's picking up very large pebbles and trying to eat those. They do have free access to appropriate grit at all times, but she doesn't seem interested in that at all.
She also seems to be standing around in the "I don't feel good" hunched up chicken stance, tail down. However, she's not always like that. If she standing like that and I walk up to her, she'll run off looking perfectly normal, and go about her business of scratching and pecking. it's very cold and sometimes it's not clear if she's just fluffed up and warming or fluffed up and in pain.
Some other context:
-Her poop isn't quite right; mostly white urates and limited solids
-She had an issue with sour crop back in the fall. I truly didn't think she was going to make it, but just when we both were seeming to give up, she turned the corner and started thriving again. Regained the weight she lost.
-I've been checking her crop morning and night. It is filling up and emptying, so I don't think there's an impaction.
-The timing of this coincides with the first week the ground has been fully frozen and completely covered with snow. This means they had an abrupt halt to their free ranging. The temperatures have also turned very cold (10-15*F overnight) after being unseasonably warm.
I'm not totally sure what to do here. I'm obviously not with her all day, but I don't see her eating much at the times of day when she's usually top of the pecking order and controlling the food bowls. She hasn't lost noticable weight yet but I'd prefer to avoid that. It seems like the wrong time of year to worry about worms (it's been consistently below freezing) and they are confined to their large run almost all the time now because they won't go out in the snow and ice, so not foraging into things they shouldn't. Should I be doing anything besides just watching?