I had sex 8 days ago and 4 days ago. Protected and unprotected. Since yesterday I started to have some light bleeding. Today the bleeding has continued. Could this be implantation bleeding? Today is my 15th day of my cycle so I feel like this is a little early. And whenever I have spotting during ovulation it is so much lighter. Has this happened to anyone before? Could I be pregnant? Or could this even be a sympotom of an std?