Hello, one of my 5 month old chickens is acting sick. He is lethargic, feathers ruffled, and won't eat or drink. He just stands alone. I have him separated because last year some of my chickens showed the same symptoms and died ( I lost 80% of my flock). Does anyone know what this disease is and if there is a cure? I don't want what happened last year to happen again this year! Please help! Thanks.