Period or implantation?

Had a one night stand about a week ago, he didn’t cum in me so the only possibility would be precum. I took plan b 2 days after. Ive had terrible anxiety and haven’t been able to eat. I usually start around the 17th. I just went to the bathroom and had very very faint spotting when I wiped. Do you ladies think this is implantation bleeding or my period about to start a little over a week early?