Here's my story.

I first got a BFP at 12dpo. The line was very strong too. That evening I started getting brown spotting. Like you would get at the end of AF. There was a fair bit of it, but only when I wiped. Of course I freaked out & thought I was having a chem preg. The next day I stayed home from work to monitor it. The spotting did ease off throughout the day and ended up lasting for about a week. I had my hcg levels checked & they were strongly rising. I figured that as it was brown, it was old blood & nothing to worry about. Until... another week or so later (I would've been around 5weeks at that stage) I got some pink cm after I wiped. It was quite feint & once again I went home to rest. The next day it got a little heavier & at one point I wiped to find a show of bright red blood. It happened about lunch time & was only red once. It then turned brown again. But the next day I started getting cramps. They were like the implantation cramps but I was so worried as I had read in this thread that red spotting combined with cramps was not a good sign. The cramps lasted all day long. The brown spotting did ease off but it continued for another week & a half. I had more hcg tests to find my levels were still rising strong. In fact, they were on the higher side of the normal range. Eventually the spotting stopped & my ultra sound at 7wks showed a perfectly normal, live fetus.

Although I still have another 4 weeks or so before I am in the clear, at this stage it looks like everything will be ok.