It can be very hard to diagnose a sick hen. Sometimes it takes until after they die, when you can do a home or professional necropsy and look for a cause. Since she has not laid in awhile, it might be a reproductive disorder, such as internal laying, impacted oviduct, salpingitis, egg yolk peritonitis, or ascites. Ascites is fluid collecting in the lower belly from EYP, heart failure, or kidney disease. Oviduct cancer is another possibility.
Feel of her crop first thing in the morning to see if it is empty, full, hard, or puffy. It should be mostly empty before she eats or drinks. Crop problems can be a primary problem, or secondary to some other problem.
Chick her all over for tiny bugs (lice or mites.) Most chickens will eat cooked egg almost until they die. My poor dead hen who I just necropsied today, ate most of an egg yesterday. She appeared to have had some sort of cancer.
Feel of her crop first thing in the morning to see if it is empty, full, hard, or puffy. It should be mostly empty before she eats or drinks. Crop problems can be a primary problem, or secondary to some other problem.
Chick her all over for tiny bugs (lice or mites.) Most chickens will eat cooked egg almost until they die. My poor dead hen who I just necropsied today, ate most of an egg yesterday. She appeared to have had some sort of cancer.