Bleeding 12 days before period is due!!

Emily
Hello! I am having a bit of a dilemma/:
​My cycle is VERY regular. 28 days, with my period lasting 4-6 days. I have always been this way! 
​12 days before my period was due, I noticed some spotting. And it was really only when I used the restroom and wiped.  The flow got a little bit heavier, and so I have been using panty liners. I'm going on day 2 of this extremely LIGHT flow! It seems to slow at night. I have no cramping but some fatigue. Other than that, all is normal.
​Does anyone have any ideas at what might be going on???