Apologies if this isn't the right forum, but it is fitness related.

I'm having problems with my blood pressure that have kept me from being able to exercise and I'm hoping someone can help me find a solution. My problem isn't high blood pressure. In fact, it's the exact opposite.

To put things in perspective, I'm 6'1", 185lbs (last time I checked). My body fat is around 9%-10% according to a hand held meter.

Last November, about one month after switching to a primal diet, I stood up quickly, passed out and during my descent hit my head on an inconveniently placed desk. Other than a mild concussion, the only thing that the doctors found was that my blood pressure was low, and I was a little dehydrated. My BP was 90/74 that day. At a follow-up visit a week later, my BP was 90/68, and a week after that it was 92/68. I made sure to be well hydrated for both of those visits.

Since then, I've been having spells of lightheaded-ness when going up even a single flight of stairs, or just about any other exertion. When I passed out, I didn't have any warning at all - I just woke up on the floor. This has made me very hesitant to exercise.

Does anyone have suggestions to help work around this? I have plenty of energy and I feel like I need to get out and move. Other than staying hydrated, my doctor hasn't been able to offer any suggestions though.