Implant bleeding

Hello. 
I had unprotected sex around the time when I would have ovulation. 
Just some day after one of the unprotected sex, I felt something was going on in the body. 
I only knew there was something. 
I was almost sure I would get pregnant! 
But it's strange, about 7 days after ovulation, I get a bleeding.
 Only in the morning was brown, thick blood. Put in a tampon and waited a while, then I switched and it was still brown, thick blood. Some red drops came when I pee. 
Later in the day, thinner and thinner blood became, now darkred. 
 Not very big bleeding but still more than you can read that an implantation bleeding should be. 
The next day I start bleeding clear red blood. Much more, sometimes like its "flow down" and then it was a little more than a normal mensturalbleeding. 
 then it stopped and only got small splashes, then it continued as a bit less than a normal menstural bleeding. 
Today, I almost stopped bleeding, day 3 today. I uschally have menstural 6-7 days from the first bleeding to the very last. 
 It is still clear red blood but only in small dishes and there is too little blood to use a tampon. 
May add that I had "menstrulbackpain"every day since the day when I started to feel something different in the body, more or less dependent day. Mostly in the evening. 
I had sex the day I blew the most and during sex there was a lot of blood, more than a while. Perhaps it "irritates" a bit and that's why I bleed more that day. In any case, my question is then, this could be an implantation bleeding? 
Or is it my period coming earlie?