Hi Steve,
First of all, I'm really sorry to hear about your grandfather's passing. I can definitely see how that whole experience could trigger some negative things happening after.
I can definitely relate to feeling uncomfortable in stores...it seems the grocery stores around here get bigger and bigger and brighter and brighter.
Have you checked with your doctor to see if maybe have an inner ear problem? Another thing is sinus problems...last year when I had a couple sinus infections, I was dizzy a lot. I don't know if that's helpful, but at least it could be something to knock off the list.
And as for what happened after you smoked a joint, well, um, can't help ya with that one. (Just Say No!) Maybe someone else here had a similar experience?
I'm sorry that you feel like you've "turned out" poorly - it's not your fault! I know that's not much of a consolation coming from a perfect stranger, but if you can try focusing on something you like to do at home maybe - playing music, art, writing, whatever, you could see that there's more to your life than this disorder.
Oh, and by the way, I've heard that if you feel like you're going to pass out, you should tighten the muscles in your thighs and calves...I assume until the feeling passes (I heard it on Dr. Phil, and then I had others agree)
Take care.
betty