Went out to our coop this morning and found our 6 week old Pekin dead. No symptoms and no trauma. He was fine when he went to bed. Yesterday morning when we let them out our 6 week old Swed wouldn’t walk. We thought he hurt his foot or maybe Niacin so we added niacin to the water. There were 7 ducklings all the same age houses together. Should we be concerned for the rest of our ducklings?