...Orthostatic Hypotension Syncope.
What's that you ask?
Here's the basic explanation:
Orthostasis means upright posture, and hypotension means low blood pressure. Thus, orthostatic hypotension consists of symptoms of dizziness, faintness or lightheadedness which appear only on standing, and which are caused by low blood pressure. Only rarely is spinning vertigo caused by orthostasis.
Yup...a head rush.
This site, http://www.dizziness-and-balance.com/disorders/medical/orthostatic.html
gives a lot more information about it. In my Google search I came upon Merck's website which gave a LOT of information that, unless you were a doctor, you'd probably have a hard time understanding much of what is written. (Yes, I understand the words on the Merck site but the medical concepts I'm a bit fuzzy on not actually being a doctor!)
I have an appointment tomorrow with a cardiologist who specializes in low blood pressure.
I've had this all my life but I think the stress of the last couple of weeks has exacerbated it even more. The last time I passed out from a head rush I was about 17-18 years old. Usually I just feel light-headed, a little dizzy and sometimes I get tunnel vision. But it has never happened at Kung Fu nor while I'm flying. I guess my heart is pumping hard enough during those times to keep me going!