Greg;
I've had several clients in the past few years that described symptoms such as yours. It turned out that some of them were actually having some seizure activity. I'm not saying that there is an organic cause to your symptoms, but it might be worth checking out with a physician/neurologist. Just a thought.
Mark

Though inland far we be,
Our souls have sight of that immortal sea
Which brought us hither.
William Wordsworth (1770–1850)