Mine gets really messed up when I use Humaworm, too. It scared me at first, but I have come to expect it. I take birth control pills straight through -- do not take week of placebos because of BAD period issues -- and do not normally have a period. I have a MAJOR one when taking Humaworm, even though I have not taken a break from BC pills.
You are not alone. I would assume that since you and I experience issues, many others probably do also.