I understand now

So you would say that she was lethargic?
If you feel an egg right below the vent under a layer of thick tissue, I would have to take a guess and say she laid internally.
Have all her eggs been "normal" no soft shells, wrinkled or lash eggs?
When you feel her crop first thing in the morning before she eats/drinks, is it empty?
Her drinking a lot of water - she may be a bit dehydrated since she didn't feel very well for couple of days and was not drinking. But I would check her crop in the morning to make sure there's not an issue there.
What do you feed your hens including treats?