So, you're having 1-bm a day, no urgency (I assume), have pain, and a sign of blood. I see no reason not to continue the taper as scheduled and play the wait-and-see approach. The bottom line is UC is anything but consistent bm-to-bm, and likes to throw lots of random things at us without warning. One episode of blood (guessing) is hardly cause for concern.
Regarding the pains, have you been having them consistently all along, even on higher doses of pred (guess)? If so then I see no reason to think a lesser dose of pred would resolve the pain.
If you had 6-10 bms a day, blood and urgency, and your doctor wanted to continue to taper then I'd call him a madman lol. However, with 1-bm a day it's perfectly sane
There's no magic pred taper schedule, and being on pred longer does not produce better results than short courses. So, I would agree get off of the pred at the planned rate/schedule. No sense in delaying the inevitable: you're either fine without pred, or need stronger meds. You only know if you can get off of pred and stay stable without pred for a couple months.