Help please?? Any one know??

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So i started my birth control about 24 days ago and my period is due in four days. I skipped my period two months ago and started birth control a few days before I was supossed to get my period. I'm now spotting a bit more than i think is normal but I also have cramps and feel nauseated. The blood isn't dark brown or light pink, it's about the same color as if you had cut your leg. Does anyone know/ have any experience of what's happening?? Also I'm under 18 and I believe it's a low hormone birth control. I'm also not using the pill for birth control. I'm not having sex, my doctor prescribed it to regulate my period and to clear up acne. Please give any tips or knowledge if at all possible!! Am I spotting or did I get my period before I was supossed to?? I would really LOVE ANY advice!!!