On the same day I said I was feeling better, I started feeling a bunch worse again. I think there might be a feedback loop where when I start feeling better, I get excited and do a bunch of work, but then I'm not actually up to it and I get burned out again. I don't think this loop is actually bad (like I'm not hurting myself, I just have limited total energy, and I happen to spend it in that pattern). But it does make things sort of unpredictable.
The next day, I started taking tianeptine, an atypical antidepressant. It's definitely been making me feel better, although it's hard to tell yet whether it's treating the underlying problem. I might write sometime about the subtleties of its effects, but I don't have the energy to do that right now, since I already did a bunch of work today.
Specifically, today, I did manage to write another thousand words or so in chapter 4 of Ravelling Wrath – the first time I've managed to work on it since November 1. It's up to about 2800 words now!