Whew! OK, first to answer Judy: this is a new vet that we hadn't been to before because the closer one didn't have a vet on-site today (why I don't know) and we weren't willing to wait.
Mary was very pleased with Dr. Hutcheson, though, who has 24 snakes himself, including kings, milks, and a long-nosed tree snake (shades of name that herp!). Dr. H was convinced that Seymour was going to have parasites but did a fecal check and he was totally clean. What I was concerned was torsion or impaction turned out to be a build-up of fluid from his RI that made it down into his colon and intestine. It turns out it had just gotten that bad. She's to give him shots every three days (I don't remember what it was but not Baytril) and bring him back in if he doesn't get better.
So, hopefully Seymour will respond to the meds, and we now know what RI fluid build-up looks and feels like for future reference, and we'll get experience giving snakes shots. Oh, and it looks like we've found a herp vet to remember (two, actually, Dr. Jason Hutcheson and Dr. Mimi Shepherd). Not a bad outcome, at least as long as Seymour responds.