I would agree that photos may help. Perhaps she was injured. She sounds like she is sick though, and giving her a real going over to check her for egg binding, crop problems, and look at her droppings may help. Feel for weight loss, look for lice or mites around her vent, and make sure that she...
She may have what is called wry tail, a common deformity. It doesn't affect their ability to lay, or hurt them in any way, but it can be hereditary, so I would not hatch any of her eggs. For people who show chickens or breed for proper breed standards, it is a disqualification. I had a handsome...