Lezlie, there are quite a few causes of odiferous and diarrheic droppings and so we perform a few tests to see if we can clarify which cause(s) are present. Important considerations are an enteritis (inflammation of the intestines) by bacteria, fungi, viruses, or toxins; intestinal parasites (helmiths, protozoa) - unlikely to be the problem in a 10 year who had been well until now; proventricular dilatation disease (avian bornavirus), chlamydiosis, Macrorhabdus (previously known as megabacteria or avian gastric yeast), liver disease, zinc and lead poisoning, and a change in diet.
My diagnostic work-up on Spike would include culturing her droppings and performing a basic avian diagnostic panel of blood and urine tests. Has her vet recommended this type of testing? Pellets are a good idea if you can transition Spike to them slowly. I have no objection to human foods, however. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat.
Please respond with further questions or concerns if you wish.