Dug around and found my service records. Took my service medical records to the only place I could find that had a microfiche reader hooked up to a printer. Skimmed the records, printed things out.
Found a lot of interesting info. So...yeah. Gonna take the printouts to my neurologist appointment. At this point there seems to be beyond sufficient info to warrant an MRI of my head. And, as it so happens, if an MRI is done then we'll know almost definitively. So...hey, maybe I'll know by Christmas (neurologist appt friday, day after Thanksgiving).