I always spot for a few days before AF, although a high strength B vitamin has helped with this over the past few months. The spotting is always brown, and there's not much of it. I have a 14/15 day luteal phase.
This month however:
11dpo lunchtime - I was wiping and I saw a lot of bright red blood. I was so surprised I thought I'd somehow injured myself below! 
That was how unusual it was! This has never happened before.
12dpo - nothing, no spotting at all. This seems strange?
13dpo - brown spotting
14dpo (today) - dark brown spotting, more of it. AF due Sunday.
If it wasn't for the bright red, quite heavy gush on Tuesday lunchtime then I would simply presume this is AF on the way as normal. I have tested but they're negative.
I'm just wondering if there's ANY chance this could be implantation spotting, and so I'm posting to see if there are any similar experiences?! 