After reading up on the condition, and examining the fit of my workshoes, I have come to the conclusion that the thing on my left foot is, in fact, a bunion.
Hotter has named him Paul.
Paul must die. Because I am not down with having a fucking bunion. The first thing I did was to stop using my custom orthotics temporarily, which created more room inside my shoes (I'll replace them the day after tomorrow, a.k.a. PAYDAY). This alleviated 90% of the pain by itself. Next, I acquired a pair of these:
Figure One: Good night, Paul!
I figure my hypermobile joints will, in this case, work to my advantage--Paul can hopefully go the fuck away almost as quickly as he popped up with the proper encouragement. Finally, I got these toe-spacer thingies to wear inside my sock during the day to keep my big toe and second toe appropriately separated.
Paul is going DOWN. If he's not gone in a month, I'll ask my doctor about him (I have a physical scheduled mid-Septemberish to generally kick the tires and discuss Paul, that weird thing my heart was doing for a minute, my TSH level, mammograms, and other fun stuff).