Well, today hasn't gone quite as we had expected.
About 30 minutes after we returned Nicolas to his cage this morning, we returned to find blood splattered all over the cage — like the scene of a slasher film!

He apparently had begun pecking at the sore, it began bleeding and he flew around spraying blood all over the cage. He lost quite a lot of blood (probably no more than 7-8 drops — although it looked like much more from the way it was sprayed) and was sitting quietly puffed up on his roost, his plumage stained with blood on the side the sore is on. Was surprised he could even survive so much blood loss.
I instantly grabbed him, covered the sore with styptic powder and returned him to the travel cage; he froze and began closing his eyes, as if he were dying, clearly very weak. We rushed back to our vet again (almost an hour away) — for the 2nd time today. He now says he is certain it is NOT a feather cyst....it's definitely a tumor.
As soon as we got there, they immediately gave him fluids to stabilize him and replace the blood he lost. He seemed to be doing much better by the time we left....he was sitting on his perch, fairly alert. The vet said he even tried to bite him during treatment. LOL So that's a good sign. (The vet also had trimmed his nails for me this morning — so at least that's done now.)
As long as Nicolas is feeling strong enough, the vet wants to try surgically removing the tumor Friday morning....with the obvious risk of him bleeding too much and not making it through. One big thing he's got going for him: He's extraordinarily strong and healthy. If any finch can make it through the surgery, he can (if today's blood loss hasn't weakened him too much). He's the best singer, full of personality, and most acrobatic and care-free bird we have — routinely turning complete circular flips to "show off" for us whenever we're around. At just 4 years old, he has far too much energy and life left in him to leave us just yet. So we're hoping for the best. But it's time like this St. Francis hears from us more than usual.
Here's one of my favorite shots of him, in a more care-free time.