This happened last night about 11:00 p.m. with my Shamrock. I posted another thread about what he has been going through with cancer & foot sores. This is just kind of a vent for me and a call for emotional support. Shammie is all right for now, and I’m taking him to the vet tomorrow.
I think it was his foot but what happened was I was sitting here at the computer & heard him from the bedroom make a strange noise, sort of a squeal. I went in there and he was kind of half slumped over. Looking not so good. I feared it was the beginning of the end. 
There was blood here and there – I gently picked him up and it was mainly on the top of one hind leg. I thought the sound he had made was like he’d coughed up blood. Anyway I took him into the bathroom to try and assess what was going on. I couldn’t see any blood around his nose or mouth but as I said in the other thread he’s getting frail and does NOT like being handled.
And before I could do much else, he bit my forefinger of my left hand – clamped down and wouldn’t let go!
I had to lower him to the floor to distract him. Then I dealt with my finger which was also bleeding.
Anyway, after watching him awhile I couldn’t tell anything about what was the actual problem, and he was on his feet and acting as normal as he can these days. I ended up putting him back in his cage and giving him some Metacam and just observing for awhile.
My finger throbbed all night – it’s okay, I don’t hold it against my boy
who was obviously frightened and hurting. It’s just so distressing when this kind of thing happens. I suppose in the end I’m thankful it wasn’t some horrible thing. It’s hard, though, with the elderly buns – you want to have them around a long time and every day is precious but also fraught with crisis at times and uncertainty and each day draws closer to that one day you dread. 
Thanks for letting me get it out of my system so I don’t get full of anxiety and sadness.