I have that too - so you aren't alone

I have a great cardio electro doc & autonomic clinic. I am on 3 medications and that helps me greatly. Took a while to get my under control. *note this is not the same as a simple vaso-vagal event, but many uneducated docs assume (or were taught) otherwise.

Here is quick rescue trick-

If you can't sit/lay down and feel it starting- Cross your legs back around each other & grip muscles tightly (almost like a little kid's severe pee-pee dance lol), then slightly bend/squat. It forces blood to CNS and really helps *if* you do it soon as you start the sensation of crashing. Release the grip slowly once the felling has subsided - if you stand up normally you will crash hard.

This has kept me from passing out several times. i.e. when standing in line or waiting to go in someplace. I usually just tell people who may notice "Oh, I have a bad cramp in my leg and am trying to work it out"

Effoexor did nothing but make me tired. Studies have shown that it is not really that helpful, mainly tried off label as it was an older teaching about 15 years ago. Often the key is finding the correct medication(s) cocktail and dosages.

I happen to take metoprolol, florinef and midodrine, but mine is consider resistant to treatment.
Good luck getting a handle on this and having much less symptoms.