Can anyone help? Maybe TMI

So I came on my period ( or what I think is my period ) quite a few days early. I've had no cramping which is very unusual for me as I'm usually in quite a lot of pain with it! And it is really light compared to normal. This is my third day and I'm so light it's hardly noticeable apart from a bit of light pink when I wipe. The only other very unusual thing for me is I have really intense lower back ache, it's so painful.
Has anyone every had anything like this before? Or can anyone offer advice before I make an appointment at my doctors? 
Only concerned as this is very different for me and my partner and I are ttc.