Thank you all for the information.

I left off a few details previously, and realize some others may need
clarification.

   On Migraine v. Meniere's v. BPPV :

I do occasionally get lightheaded from standing too quickly (or from
looking up), but this feels totally unlike that.  That lasts seconds,
is totally blinding, and goes away pretty quickly.  This seems to be
episodic in that it lasts for the better part of weeks, and then goes
away for months.   This morning - like every morning for the last 10
days - I woke up and felt absolutely fine.  No headache, no
dizziness.  I stood up and still felt fine (i.e., the act of standing
did not produce symptoms).  Within 10 minutes I felt lousy again.

All of the stuff I read about vertigo talks about "spinning," which
is not exactly what I'm feeling either.  (see prior post).

   On red herrings:

My ears do feel really stuffy right now, but I don't think they did
during the other courses of this, so it seems like that may be a red
herring.  No tinnitus, as I understand it.  The ear stuffiness is
likely seasonal allergy related (northeast USA), but since the last
bout of dizziness was February it would have been hard to say that
then.   There is a "noise" in my right ear when I open my mouth - -
sort of a crunchy/grinding/wet noise.  That preceded the vertigo by
quite a few weeks, though, and again I don't think it existed for
other bouts.

   On contradiction:

One thing that is really confusing me is that as disoriented and sick
as I feel - - I was able to go for a hard 6 mile run last night, and a
45 mile bike ride the day before - - and neither made me feel any
worse.  In fact, I think I felt briefly better.  Is there anything
about raising my heart rate or endorphins that could account for this?
Would either have an effect on fluid in my ears?  I know you're
tempted to think, "hey, if she's exercising that hard, the symptoms
can't be that bad." But you should resist that temptation.  I'm
devoted beyond  the logic of pain.  (A few years ago I broke my foot,
was told by a doctor that it was nothing, and continued to run on it
for years until an x-ray proved the fracture.  Yes, it hurt.)

   On hypochondria:

BUT ... the reason I'm seeking anonymous usenet/internet information
and not going to a doctor - - is that about 5-6 years ago, I suddenly
started experiencing a lot of numbness in my body, especially the left
side of my face, but also elsewhere.   Duly concerned, I went to my
physician, who sent me to a neurologist, who did all of the appropriate
tests and found nothing.  She specifically ruled out scary stuff like
MS, lupus, thyroid, diabetes, etc.   It was dismissed as "anxiety"
and I felt like an idiot.  A crazy idiot at that.  The numbness in my
face (and elsewhere) wanes at times, but it is fairly strong now.
It's hard not to want to tie everything into a "single disease
theory" but I think I'm supposed to know by now that it's best
not to think about it, lest I become known as an even crazier idiot.

That was too much information.  Sorry.  I guess I'm just feeling a
bit frustrated.

- Wanda