OK, so there's enough information in the previous paragraph to tell you exactly what I've been doing today. Up most of the night in screaming agony, slept intermittently all day, waking up going "argh" and taking more drugs. Am now approximately vertical but stoned out of my head in an opiate haze.
I haven't had pain this bad in *months*. Mostly because I've been very, very careful about what I eat. I thought I was good enough at evaluating whether food was likely to do me harm. Obviously, I was wrong.
I'm so angry at myself.