I think @Eggcessive covered about all of it. Perhaps the fowl pox is contributing to the respiratory symptoms in its small way, also, if it's partially blocking the nares.
Squirrels seem to have an affinity for chickens. Here they sure do. They come into the run sometimes when I leave it open for the chickens to free range and hilarity ensues when the dumb creatures corner themselves and panic trying to find their way back out. Picture a billiard ball bouncing off the rails. One time one squirrel was so dumb, he couldn't find his way out and spent an hour digging a hole under a corner in the run to escape. I took serendipitous advantage of him finding the single vulnerable spot on the run and sealed it off after he got out.
Squirrels seem to have an affinity for chickens. Here they sure do. They come into the run sometimes when I leave it open for the chickens to free range and hilarity ensues when the dumb creatures corner themselves and panic trying to find their way back out. Picture a billiard ball bouncing off the rails. One time one squirrel was so dumb, he couldn't find his way out and spent an hour digging a hole under a corner in the run to escape. I took serendipitous advantage of him finding the single vulnerable spot on the run and sealed it off after he got out.