Call duck falling and bad feathers?

[Babyquail]

I have a call duck and a 2 month old Swedish Duckling, and they are in a coop that is off the ground (predator problems) and is fine wire on the bottom, I noticed my Call would take a few steps and then fall on his stomach, and in the yard he didn’t limp, but stumbled a few times. He also has pretty ruffled feathers, and is losing a lot, and his tail looks very ragged. The duckling is fine, and they don’t fight at all, in fact they are inseparable. I am adding vitamins to the water, and makeing sure they have sufficient food, anything else I should be doing or worry about?

 

[Babyquail]

Video of him and coop, he didn’t fall but you get the idea