First, my humble thanks to everyone for the sympathetic Tap-Repeatedly response to my unexpected medical adventure(s). I continue to be warmed by your kind wishes and can happily report that I am healthy, active, and glad to be alive.
I can also report that I think I have finally solved the mystery of why I was bleeding in the first place. Sort of had to. None of the medical professionals I interacted with had any explanations to offer, so I became a detective on my own behalf. This is that story.