Very sorry for your loss. The state poultry lab could look for what might have killed her. Respiratory diseases can lead to air sacculitis and death at times. You could get a diagnosis if the necropsy is done. What did you worm her with? Many folks in Florida worm their chickens often due to the climate. SafeGuard given 5 days in a row can help treat gapeworms, one of the more rare worms. Respiratory diseases can be bacterial, viral, or fungal, and antibiotics may help treat symptoms of bacterial diseases. Most respiratory diseases are chronic and will last for the life of the chicken, also making them carriers.