Thoughts, experiences..af or implantation

Ok, so I had to go off my bc becuase it negatively impacted my mood to an extreme. I was on it two weeks, then off. I watched opk tests, but turned out they were faulty. So I don't know if I ovulated. I had sex 10 days ago, and have had some symptoms that could be pms or early pregnancy. So today when I started cramping I was releived. But...it never came. So i checked my cervix, high, closed, and there was some dark red/purple blood. It wasnt bright red. Those who implanted, what day after sex and what color. I'm hoping this is just an umusual sneaky period