Well in the last few months I have been occasionally getting (once a week or less) a strange problem. My vision slowly becomes lost and everything starts to blacken, although I can still talk and walk etc, my hands get pins and needles and my vision slowly returns with some head pain.

Any ideas what the issue should be? The blackout usually lasts no more than 10 seconds, yet when it occurs I have to take a seat as I feel I could faint at any minute.