Just an update --
Because of Covid, I couldn't get to see a GI in person. They offered me video visits in 2-4 weeks. The on-call doctor prescribed Cipro, which I didn't take because I'm so sure from how this feels that it's a structural issue not pouchitis, which I never get.
Here's what I did to feel better: I sat in hot baths with epsom salts. I sat on a heating pad. I put a little petroleum cream just barely inside with a cotton swab. The difficulty empty got better. It stopped feeling that there was something in the way for emptying. The amount of blood went down.
I spoke with my internist via video and he agreed that I shouldn't take the Cipro and I should give this a little more time. If I don't continue getting better or if it gets worse, he's going to help me find a GI who will actually see me in person to take a look. From what I described to him, he felt that it was probably a small fissure, just as Jan has said above. 
The problem with the pouch is that I panic if something isn't right (and is painful!) because I don't know what's going to turn out to be serious/ongoing and what's just a temporary issue. When I had UC, I knew every feeling/symptom perfectly and knew what to expect.
I'm grateful for this site. I think every GI treating j-pouchers should visit here to read about what it's actually like to have a pouch.