Good news, everyone! (And many thanks for the replies.) My doc wanted to do the sigmoidoscopy (quite a blast from the past!) and the colon itself actually looked great. (Yay!). It was hemmies!
So, here to say you can definitely have some on-again, off-again blood and pretty bad rectal pain and it may just be an internal hemmie. Always good to check, though!
Only with UC can having an internal hemmie be 'good news.'