Implantation bleeding vs. periods

This morning I went to the bathroom & I wiped & I had light pinkish blood & the second time I went to the bathroom I wiped & it was dark red & brownish. I have mild cramps. My period is not until next week. What is this? Is this just a scare? The arreolas on my boobs are darker, my lower back hurts, & when I eat something that I've been craving I feel disgusted afterwards. What is this?