Hi, I recently hooked up with a guy and we got naked and I had oral sex with him and he ejaculated not near my vagina. Then he cleaned up and we started grinding on each other while naked his cock was rubbing against my vagina and there might of been a bit of precm. Can I be pregnant? I was supposed to get my period but instead I got brown stuff instead of red blood with a bit of spotting for 7 days. Could this be implantation bleeding?