Richard, I have the same problem. My blood pressure drops about 20 points when I stand up too fast, I have had this since 2009. I went from doctor to doctor in search for a reason as to why I would get so dizzy. I finally saw an ENT who did a battery of tests and he called this "postural hypotension". There is nothing you can do when you get this and the only thing that helps me is that I have to watch how fast that I get up after sitting. Sometimes I forget to get up slowly and the extreme dizziness reminds me.