aaaaand back from the vet. We did three films and took blood. He's got some arthritis (age-appropriate) and there's a shape on the x-ray that could be a kidney that's the wrong shape and in the wrong place (not a problem as long as the other one works) or that could be what we euphemistically term a mass.
But he seems to have stopped vomiting. We're going to try some rice and poached chicken in a little while. I am less panicky, though, which is good--because I know whatever's going on, we're taking whatever action can be taken.