I have recently recently bought two new runner ducklings to add to my flock. I bought them when they were 6 days old, and they are now,3 weeks old. The younger one is perfectly fine but the older one seems to have breathing problems. He sometimes has his beak wide open, and also makes load noises when he breaths. I'm pretty sure he isn't over heated because he lives inside without any heating equipment. Should I give him any vitamins or medicine? Can I have some help on this please?