What’s happening?

I’m a 17 year old Virgin on the pill. The past two months i have been getting brown spotting before i have even taken the white tablets to bring on my period. i have like 2 more days until i take my white pills and i’m spotting brown stuff. Is this normal? It has only happened twice but other than that it has never happened before and i’ve been on it for around 6 months or more. I’m on anonymous so i won’t be able to reply.