I've been taking birth control for over 4 months now. However, I was accidentally late on taking the pill the day I had unprotected sex (which I also practice consistently). I was about 6 hours late and I immediately took one pill, then resumed to taking my pills on schedule. Today, I noticed a period-like vaginal discharge. In my 28 days pills cycle, I am 3 pills away from taking the 7 placebo pills. I'm quite worried that this is implantation bleeding, however, I know that this can easily just be a hormones problem. Should I be worried? What is most likely the cause of this problem?