I had unprotected sex with my partner on 2/23/18 and have been feeling strange ever sense. A weird bloat/rock type feeling in my stomach that I've never felt before, light cramps and back pain (though I have chronic back pain) and also frequent headaches (and I'm also prone to headaches too), nausea(with some vomiting but not limited to morning) as well as sore breasts (which is NOT a typical period symptom I get). Today, 3/5/18, 9 days after the unprotected sex, I've started bleeding. It would be about 1-2 weeks roughly until I'm due for my period. Could this be implantation bleeding? I have light cramps but not like my typical period, usually I'm doubled over in pain from them, these are not painful at all. Just a mild annoyance, I wouldn't even call them painful, they've actually lessened as the day has gone on. My blood is red though which I read it shouldn't be for implantation bleeding? But I've also read it can be red and easily mistaken for a light/early period. I've already taken an at home pregnancy test, yesterday, which came back negative but I know it's unlikely I've built up enough hormones to test positive. Thoughts?