8 out of 10 chicks hatched and they have been the the mother hen and all seemed to be going well until today. The last 3 days the hen has been taking them out to free range and I've been supplementing with crushed oatmeal, banana, eggs and scratch. This evening I found one of the birds far from the others with swallow breath. I checked it for pasty butt but not sure what else to do. What could it be? I don't want any of the others to die. Any advice.