It would seem that I was working under a bit of a misapprehension. As some guessed on the previous entry's notes, the rash that has now taken over my left butt and is wrapping its way around to the front is indeed shingles. I made an appointment with the doctor on call this morning (not my usual doctor), and he pretty much diagnosed it with a glance. The rash is apparently pretty recognizable among the cognoscenti, with the fact that it is restricted to one side of my body being all but pathognomonic.
I'm on an antiviral, but it's probably going to take 3-4 weeks for this to resolve. I'm hoping I'll be one of the once-and-done shingles victims, since over 50% of people never get shingles a second time. I won't be able to take any additional steps to ensure that though, since people on immunosuppressants are unable to get the shingles vaccine.
I should've asked about pain meds.