Should irregular spotting and bleeding during 2 packs of Vines bother me?

Hello. I finish 2 packs of Vines tablets. At the first package I had a slight headache and lower abdomen and the period I got perfectly with the first placebo tablet. At the second package, about halfway through, I started to stain brown and the lower abdomen pain shortly after that I got a period a week earlier than I should have. After a period of staining and slight pain in the lower abdomen did not cease. Both periods were very scarce. Is it all by getting used to tablets or should I start worrying? Thanks in advance for your reply