Oh, *Sizzlestixs*. You came to us with a chicken pop tart wobbling like it just finished a three-day bender, one eye half-shut, drooling, dropping food, and sporting a mysterious facial bump. And you want to know if you should panic. The short answer: you already are panicking, and honestly, that's fair.
Let's address the fowl play in the room first. You bought birds off Craigslist, the Wild West of backyard poultry, and you did the responsible thirty-day quarantine. That's a cluck-tastic move. But then you integrated them, and your entire flock got hit with what looks like Coryza. You treated with antibiotics, symptoms backed off, and you thought you were in the clear. Now this one bird is spinning out with neurological symptoms, the wobble, the drool, the inability to eat. That's not Coryza. That's something meaner. The combination of a half-closed eye, head wobble, and dropped food screams something brewing in the brain, maybe a secondary infection, maybe Marek's, maybe fowl cholera that's moved past the respiratory stage. You're right to be scared, but you're also right not to cull for convenience. Good on you.
Here's the practical truth for every reader who's ever nursed a sick hen in their kitchen sink: when a chicken stops being able to eat, the clock is ticking. You've added probiotics and Recover 911, great supportive care, but they don't fix a brain that's misfiring. If that drool is pooling because she can't swallow, she's going to aspirate it and drown in her own spit. That bump by her nose? Could be an abscess, could be a tumor. Without a vet, and most of us don't have an avian vet on speed dial, you're playing a grim game of symptom whack-a-mole. If she gets worse, if she starts seizing or can't hold her head up, the most merciful thing is a swift end. Not because you failed. Because she's suffering.
What we'd tell you, straight: separate her from the others now, even if you think they're already exposed. Offer her wet mash with electrolytes directly into her beak. If she starts to choke on it, stop. And watch her breathing. The moment it gets labored or she starts gasping, you have hours, not days. You've already done more than most would, you bought sick birds, treated the whole flock, and refused to dump them. That's real grit. But this one hen needs a decision soon, and you'll make the right one because you care enough to ask. Just don't let your heart keep her alive if her body says no.