We're back from seeing the vet. Looks like Stuka has a serious secondary infection from a plugged crop. When the doctor was examining him, she pressed on his throat/chest area and Stuka threw up all over her. Joy. She said she could feel a large mass of seed and mucus in there, which she flushed out with a syringe-like instrument. While we can't be 100% sure, we're all hopeful this was the main root of his illness and, now that it's resolved, he'll start feeling better soon. Since he had so much bacteria in his poop and crop, she isn't comfortable with just diluting the antibiotics in his water like she'd normally recommend. We have to give him a full strength dose orally via syringe once per day for the next 7-10 days, then call her with status to see if we need to do a second round of meds. While we're not out of the woods yet, it looks like he's going to be okay and live to torment us another day.