Brown blood means old blood, could take some time between the initial bleed and actually seeing it. As it has been over a week there is no harm in getting checked out to put your mind as ease. With my first two pregnancies i had implantation bleeding. I am now 7 weeks too and not had any up to now. Call your midwife/ doctor and they should put you at ease x
I'm having similar worries. Right after getting my positive HPT almost 3 weeks ago I had brown spotting. It lasted for a few days and disappeared. I figured it might be implantation. Then on Sunday (two weeks after positive HPT) I started spotting again. It's not a lot, just when I use the restroom and it is either a very light brown or a very light pink. Sometimes there is a tiny tiny tiny streak of red, but I mean small. I have had blood drawn several times. First week after positive HPT it was 103. One week later 2000 and yesterday it was 15,000. I just have to wait and see. It is very terrifying I know but it sounds like it is pretty common. Hang in there and I will try to as well! I hate all this uncertainty in the first 12 weeks!