Dark then bright red period. Can someone explain pls??

Ok so for the past two weeks I swore I was going to miss my period I had unprotected sex with my boy friend and thought I got prego. I was having ALL kinds of symptoms sore/tingling breast cramps food aversions moods swings fatigue nausea. You name it I had it. I even took tests that I thought were either faints positives or evap lines. Until, I came on yesterday which was a day early, it was suppose to come today. This is the thing though the day before I came on I was feeling horrible, either I was having some STRONG PMS for a couple days or something was wrong. I couldnt even function at work and when I got home I couldnt even sleep after a 13 hour shift until 2am after I finally took some meds because of the pain I had. When I started bleeding it was VERY, and I mean like VERYYY dark like burgundy. Then stopped for 10 mins and got BRIGHT red and watery and it was more than usual (sorry tmi!) But its usually thick, now I feel no pain. And let me tell you I just wasn't in pain before my period I was cramping and having headaches my whole dpo, and it wasn't in my head. Today is my second day and its alreday slowing down. Has any one else had a experience similar to this?