Eggcessive, Thank you for your reply.
We're in Alaska. She's one of 17 (5 Plymouth Rock, 5 Buff Orpington, 6 Cherry Eggers + an Indian Runner). Actually the Buffs appear to run the roost and generally get their way. I haven't witnessed any aggression in the flock. They have plenty of room with easy access to food & water.
I place powdered PDZ between layers of the white pine shavings inside the coop "common" area (occasionally, as needed) ...but only when hens are outside in the run. Pellet PDZ wasn't available so when using powder I'm careful to minimize potential for any respiratory issues. I don't think it's an inflamed sinus.
Still debating whether to lance this thing. Watched a similar procedure on an anesthetized parrot (youtube) . Lots of heavy infection was scraped out. Not sure if she could endure that...at least while conscious. Perhaps just opening it up and letting it drain. I've read squeezing can push infection back into other areas.