Harry Bloomfield wrote:
Fredxx formulated the question :
I can be dizzy but only after being sedantry for a while and then
doing something like running up some stairs.

I did always suffer with that, I think it's quite normal - your body
needs time to prepare for action, from a relaxed state.

This dizziness was quite different, though the same feeling of about to
pass out - looking up at shelves at home or in shops, wondering round
the isles in stores etc. all would triggering and then I would need to
lean on something, or sit until it passed.

The section on Hypertension here, has quite a few names for the conditions.

https://en.wikipedia.org/wiki/Category:Hypertension

Thus one covers postural hypertension, where your body doesn't
automatically adjust for your upright position properly.

https://en.wikipedia.org/wiki/Orthostatic_hypertension

It means your doctor has to be a whiz at memorizing trivia.

*******

The Hypotension section is much smaller.

https://en.wikipedia.org/wiki/Category:Hypotension

https://en.wikipedia.org/wiki/Orthostatic_hypotension

Paul