I have PCOS and have never had regular periods. Since having my two children (who are 2 and 6 mo) I've had one about every two months or so. I'm on day 10 of my whole30 and bam! got my period today on day 24 of my cycle. I did feel slightly bloated yesterday and was wondering if somehow I had eaten something non-compliant by accident. I knew that wasn't possible, but now I know what the cause was. It will be interesting to see what happens from now on.