Birthmark?

My babe was born in August this year (2013) and since day one there has been a small red speckled like stamp mark on her thigh. My midwife and babys Gp hadn't seen one like it before but both seemed to think it was just a birthmark and that it would fade within a few weeks. She's now 18 weeks, it hasn't faded but has maybe grown - only as she's grown though and it's seemed to have become a more intense/vivid red. It feels the tiniest bit raised but doesn't seem to be bothering her at all.
I'm not sure if it was there before it but it looks like it's in the same area her vitamin k injection was.
Alot of people have asked what it is...
I've looked in books and on the Internet and can't seem to find anything like it. I've added in a photo and if anyone can maybe put my mind to rest, I'd be truly greatful.
Forgive me if I've posted this in the wrong place.
Thanks!