Elizabeth, I'm sorry that your question wasn't answered in a timely manner. There are quite a few concerns when a budgie becomes polydipsic (increased thirst) and polyuric (increased volume of urine. These include renal disease, diabetes mellitus, diabetes insipidus, hepatic disease, pancreatic disease, Cushing's disease (hypercortisolism), heavy metal toxicosis, "phosphate flush" due to an all-seed diet, and pituitary adenoma (a brain tumor). She's going to need her avian vet (www.aav.org) again to perform basic blood and urine tests in an attempt to clairif the cause of her symptoms. They're not related to her cuttlefish.
Nutritional imbalances are a common problem in our pet birds. What has her diet consisted of, please? Seeds should compose less than 20% of her diet. A diet of mainly seed and nuts has excessive fat, carbohydrates, and phosphorus; marginal protein; adequate vitamin E, and are deficient in amino acids, calcium, available phosphorus, sodium, manganese, zinc, iron, vitamins A, D3 (necessary for efficient absorption of calcium, e.g., from her cuttlefish), K, and B12, riboflavin, pantothenic acid, choline, and available niacin. 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.