well, if you are experiencing these symptoms, i *do* think this si something to worry about...pass out and knock your head, its an issue!!
I have severely low bp myself, from diabetic nerve damage, but even before then, i had circulation issues..where i couldnt stand still for long, or my legs would swell. It helps to eat, drink, etc...all those things mentioned above...
but also, look into support hose or knee high socks even....just make sure the elastic around the top isnt too tight.
as far as figeting and moving...go up and down on your toes/ heels to engage your calf muscles, and crossing your legs at the knees (while standing) and sort of crouching a bit, so that you engage your thigh muscles... are some moves that my doc told me about.
btw, can i ask what job you have that makes it difficult to fidget? it sounds torturous!! lol.