When I had preterm labor with my 2nd child, I was put on a beta-blocker (high blood pressure med) that also had a side effect of relaxing muscles, hence, keeping my contractions at bay. I found that I was often feeling exactly as you describe... light headed and dizzy. My brother-in-law is a dr. of pharmacology, and he suggested drinking a lot of water to increase my blood volume. It helped me tremendously. I don't know if this will help you, but it's worth a try! So, yes, Bikeless (my Cindy riding buddy! ), it sounds right to me!

Hope you're able to keep biking, but keep yourself safe.

P.S. Coach K Rocks!