I haven’t used it before, except on humans in a hospital setting. But it should be similar. I think that @azygous has recommended it before. Very sorry for you r loss. If you would like to have your state vet do a necropsy where they can find a cause of death, keep the body refrigerated, and...
Welcome to BYC. Can you do a complete exam on her? Feel of her weight, look for a more bony keel or breast bone. Is her crop empty and flat, partially full, firm, soft and puffy, or doughy? What do her poops look like, including pictures. A picture of her as well. Can she stand or walk? Are her...