Damn. I'm not sure if it's a result of your cycle, but I would think it was have to be a lab error, or a side of the cycle. I do cardiology research for a living and I'm conducting a major study sponsored by Phizer (the makers of Lipitor) testing a drug called Torcetrapib, used to elevate the HDL, and out of 154 research subjects to date at my site, I've not seen anyone lower that 25-30.
I, too, would take Niacin.
kevin7