Implantation.....?

AF due on Friday.

This morning around 830am I was at work having a conversation with someone and felt some cramps in my stomach. My first thought was that I needed a poo (sorry!) It soon passed and I thought nothing of it.

Around 1130am I headed to the loo for a wee and when I took my knickers down I saw blood (brown).

I put a liner in now 5pm there is a small amount of brown blood on the liner. By now if this is a normal period I would have a really heavy flow and it would be bright red.

I still have the cramps although they have only just started again from this morning. I wasn't expecting AF until Friday, does this just sound like an early period? I'm normally as regular as clockwork.