Welcome to Healing Well. Sorry to hear that you are having problems with Topamax. As you said you know you are going to have to tell your Doctor about this bleeding, and I can only endorse that!!! Topamax is quite a potent drug and can have real benefits for the headache, but sadly it has side effects that are equally as strong!!!
Thankfully these side effects do not trouble some people too much, but I was not able to get along with it, it is a very personalised thing!!! Please see your Doctor about this breakthrough bleeding as soon as possible and let us know how you get on!
Co-Moderator of the Migraine/Headache Forum