Does she puff up and make funny noises when you get close to her, or when you reach out to pick her up in the nesting box? If she does, she might be broody, it might be likely, if you couldn't feel an egg and she keeps trying to get back to the nesting boxes. I hope this is the case for yours! Broodys aren't sick, they just wanna become mamas! They can be broken out of it by kicking them out of the boxes for a bit, until they calm down :blobheartcat:

We've had quite a few broody hens, and they've all just kind of refuse to leave the boxes on their own, and won't eat or drink without being forced to. Other hens will start attacking broodys because they get irritated and want the nesting box she's in. :animu_sigh: