Lynn, I'm sorry that your question wasn't answered in a timely manner. We don't have many avian vets on this site. Please let me know if you still need help. Charlie's jerky head sounds like tremors or perhaps partial seizures. Unfortunately, we're limited by how much we can do for seizure disorders in canaries. Treatment is supportive: heating her environment to 85% and placing her in a dimly lit unlikely to be disturbed area. Seizure disorders are most often idiopathic (unknown cause/idiopathic epilepsy) but can be of traumatic or infectious origin or related to an imbalance in Charlie's diet.
Nutritional imbalances are a common cause of illness in our pet birds. What has Charlie's 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), 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. I have to leave my computer for the night but I promise to reply in the morning if need be.