If you are on the pill, check with your doc and see if you can take them continuously (i.e., avoid the placebo pills). My doc has prescribed them that way for me for years because of horrid periods. How close in time is the ride? Could you see your doc before then? He or she might have some other options for you.

Have you tried riding on the really sucky days? I was always surprised (even with the horrid periods) at how much better I felt with exercise. I was *so* hard to get out there, but it did help. I know not everyone is that way - but it was true for me.

Otherwise, hugs and sympathy. That sucks