Hi Gretl,
From what you describe, she might have a large egg that is stuck and if left, will cause her to prolapse?
A prolapsed oviduct is when the lower part of a hens oviduct turns inside out and is left hanging outside of her vent. This condition is most common in young hens that have started laying too soon but can be inherited in some pure breeds, especially from exhibition lines.
Prolapse is caused by the tissue that normally holds the oviduct in place being damaged by the egg being forced out.
It's hard to say what to do now because it is night time and she won't naturally want to lay right now - take a look at her and make a decision what to do - if you are unsure, it's a trip to the vet - but if she is still like this in the morning, you can hold her over a bowl of steaming water (not too close that she burns) and gently try to get the egg to come out. Try not to break the egg (due to infection) but if it really will not come out, sometimes you have to break it / make a small hole in it and try to drain the contents and shell out.
Read this article on
Egg Bound Hen too...
This is usually best done by a vet but make sure you go to a poultry vet who has experience because there are many who won't be able to deal with this.
Let me know how you get on - if there is any prolapse (blood / oviduct) outside of her vent, keep her away from other chickens because they will peck it and kill her very quickly.
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