M.G.
Not during it, but just before - PMS. And I forget every month so when I go completely whacky, I have no idea why. I just assume everything is harder, more upsetting, etc. then it comes the following day and I'm like "Oh thank God, I thought it was me".
My good friend is the same - she'll text me and seems really off, and I will say "Are you PMSing?" and sure enough, she is. We're both close to 50 too.