Vet Rx is a natural decongestant that can be given straight to the duckling/chick or can be put in their water. We put about 6 or 7 drops in each of their water bowls. I swear by it! I used it for a week, and all of my chicks and ducklings cleared up. They all had some sort of sinus issue. The hatchery that we got them from, didn't seem to produce very healthy birds. We won't be going back to it.
I'm glad that your baby is clearing up! I would keep using it for at least a couple of more days. I kept trying to "stop" and the clicking noise would come back.
What hatchery did you use?