She was fine the day before yesterday and now she seems to mostly want to lay down unless I prod her to get up. She's laying eggs and clucking. I wish I could figure out how to send a video. It seems like she lame and just wants to lay down.
Is she laying in the nest box mostly? Can you insert a finger into her vent an inch or two, to feel for a stuck egg. It should feel soft if not egg is there. Look at the bottom of her foot pads for any dark scab or swelling, and look at her joints for any swelling or bruising. Touch her feet to see if she can move them or her legs if you pick her up. Make sure that she is drinking some water, and offer her some chopped egg with her feed.
A video would be great You can upload to youtube or vimeo and post the link for us. (I think that's right).
Can you tell us a little more about your hen:
How old is she?
When was the last time she laid an egg?
What type of food/treats do you feed?
Is she eating, drinking, pooping - anything odd about the poop?
When she does walk, does she limp?
Does she have any swelling, bloat or feeling of fluid in the abdomen?
How does her crop feel - is it emptying overnight?
Have you added any new birds to your flock within the last 30days?
It's so hard to know what's going on when it comes to laying hens. There's so many things it can be.
See that she is drinking and if she will eat for you. As long as she's peaceful with the flock, I would not separate her. If she is lethargic and can't eat/drink on her own, then separate her so you can monitor her closely.