So sorry you are having problems with your chicks. I have been lurking for quite a while waiting to get my first Isbars. It does worry me that they are so fragile, but they are SO beautiful that I just have to try. One thing that I have been researching a lot lately for other issues is colloidal silver. I have used it successfully at home on myself and my family, as well as our other pets, but have just started giving some to my chickens as a preventative. Purchasing pre-made CS can be expensive, but it can be made easily at home. It might be worth a try before you give up on your birds.