This happened to me as well. It was never determined what specifically it was, but it could be implantation bleeding. Also I have higher than normal TSH levels (thyroid) and that is apparently known to cause bleeding as well.
Brown blood is old blood, but always call your doctor if you bleed at all. Sometimes it's normal but it's always best to check
Sorry but happy to read this. I'm currently in week 9. I have some brownish stuff only when wiping. I had an internal scan last week and saw baby heartbeat. Then the brownish stuff happened and been going on for a week. I'm now freaking out that I've had threatened or missed miscarriage. Heading to doctor tomorrow morning for another scan. Wish me luck! I've already had 3 miscarriages and one daughter who is four.
I am also having the same problem. Started in week 6 now in week 7. Still the spotting continues.. I had an ultrasound to check my baby's health. My doctor said that my baby is perfectly fine and safe and the bleeding is due to the old blood accumulated in uterus.. So don't panic and check with your doctor immediately. Stay positive.