I'm sorry to hear of this, Marnie. Unfortunately, the symptoms you've mentioned can indicate any number of illnesses or health issues. In avian medicine, there's rarely one cause of a condition, so we usually begin with a list of differential diagnoses and use lab tests, X-rays, and physical exams to differentiate one from another. With this in mind, your best course of action is to reach out to your county-extension poultry personnel or avian-oriented veterinarian (please see here: www.aav.org) for help in differentiating the various causes of what you're seeing. Veterinarians can perform a physical exam and run diagnostic tests, including X-rays, to distinguish between the differential diagnoses.
It's best to approach the diagnostic process with a clear sense of the birds' financial value to your operation. Although some services such as your county animal disease diagnostic laboratory might be available free of charge through a county agency or land-grant extension office, the expense of some diagnostic tests and treatments can add up quickly. While it’s always worth your time and money to identify a bacterial or viral infection that could potentially impact more than one member of the flock, this might not be the case with a condition that only affects one or two hens.
If you have a sizeable flock it's important to have a recent death refrigerated (not frozen) or a very ill bird sacrificed and then necropsied. That's the most thorough and expedient manner in which to determine why your bird died. Your county animal disease diagnostic laboratory is the most cost-effective place to have that done but not all counties have such a laboratory. If not, a veterinary teaching hospital or an avian vet can tell you which resources you have in your area.
Scours can result from primary gastrointestinal bacterial and viral infections as well as parasitism. Systemic disorders outside the GI tract but which affect the GI tract also need to be considered. It's not unreasonable to worm all of your chickens with piperazine (Wazine) at this time and also treat them for coccidiosis with amprolium (Corid) - both at the dosing recommended on the product label. Ideally an avian vet should perform a fecal ova and parasite exam to determine which parasites are present but I understand that you might not access to such a vet. I regret that I can't be more specific for you. It just isn't possible from here. Please respond with further questions or concerns if you wish.