As I am sitting here reading this I keep thinking of the work 'quarantine' and see no mention of it anywhere. This is why it is so important for people to take precautions, not expose your birds to others until they have been kept away from the rest of a flock for 60 days. If they are carrying something, it will usually show up by that time. I see so many people take their birds to a vet and get the blood work down and think once the blood work comes back, you can let them join the rest of your birds. This is not correct. They can still be carrying something that does not show up in the blood work. Period.
I hope for your sake this bird is not carrying PBFD