6 days of implantation bleeding?

So basically this has all the notions of implantation bleeding. It is brown in color (occasionally rusty red) and isn't even heavy enough to stain a pantyliner. I had almost noexistent cramps and I've been experiencing extreme tiredness (sleeping twelve hours at least for the last three days) and yesterday I started on some nausea. It comes and goes and is never a constant flow and just isn't like a period. It really seems like implantation bleeding. We weren't really trying this cycle but we've been trying for a couple years. I calculated back the timeline and we had sex in line of when the bleeding began. It's just I thought implantation bleeding lasted 2 days max and now these sights are saying something different. They say it varies between women. It has stopped now except for a couple drops on the toilet paper occasionally this is day 7. Can implantation bleeding last for seven days? Im sorry if this is a stupid question. I was going to wait until Friday to test because I didn't want to do it too early because I heard if you're still having implantation bleeding you won't get a positive. Is anyone else going through this? Has anyone gone through it? What happened? Is this implantation bleeding?