I had a trigger thumb as well. Tried the cortisone shot and a custom made brace, which I wore most of the time. It helped for a bit, then got worse. After ignoring it for a while, I finally went back to the doctor and he recommended the surgery.
They did a local (and actually put me to sleep just long enough for the actual surgery - not a general, but something like versed - but brought me out in time so I could bend the thumb when the doc asked me to).
I had my stitches in for a week. It was bandaged for that whole time (no changing the bandages). Since I can't take any pain meds, I just used tylenol and as long as I took it every 4 hours, it controlled any discomfort I had.
My doc said it could hurt for about a month after the surgery - and I did have occasional pain - but for the most part, it wasn't bad. Plus, it was nice to be able to use my thumb again! I'd gotten to the point where I couldn't use a can opener or open a jar or anything like that (even holding a Mickey-head ice cream was a challenge).
Don't be afraid to go for the surgery - I put it off for many months and once it was done (and I realized it wasn't that bad), I wanted to kick myself for being afraid.
ETA: I think the worst part about the surgery (for me, at least) was not being able to get my hand wet (made for difficult showering) and having to rely completely on my DH and kids the first few days for food prep.