Are her droppings all black and tarry? If so, that might be from internal bleeding. Has she lost weight in her breast area? Can you check her skin near the vent and elsewhere for lice or mites? A pale comb can be from molting, mite infestation, bleeding, or many other problems. Can you have her seen by a vet in the morning, or take a few fresh droppings in to be checked for worms? She sounds very sick. She needs to drink some water with vitamins and electrolytes, such as SaveAChick or NutriDrench. Many older hens can suffer from internal laying, cancer, and a number of illnesses. Hopefully, you can get her to drink and eat some.