This is just a thought but often times when we try to balance problems with our body by using something natural we actually get worse for awhile. So if it was menstrual irregularity then it gets worse for awhile.....It seems as if our body just starts dumping things out of our bodies to get rid of toxins and the like. When I had my issues with my cycle (I would not stop at all...for 1 1/2 years straight!!!!ugh) I started taking the natural medicine that changed it all but first my period became heavier than it has ever been for three weeks! I started thinking I should not be taking this as it is having the opposite effect....but I stuck it out and now for the first time in my life I am pretty close to being regular.
I have heard this experience you are describing as a healing crisis.
On the other hand maybe some of the herbs are not what your body needs. Use your intuition to decide this or talk to some type of Doctor who knows herbals well. If I were you I would probably take it for at least two to three months to see how it works.....jsut a few weeks is probably not enough to tell. Good luck.