3dpo spotting

Danielle
I have had cramps since I ovulated 3 days ago, I used an opk to know when I O'ed. I have never in my life spotted, I have a very consistent 28/29 day cycle and my period isn't for another solid week. It's my 3rd month ttc, is it possibly early pregnancy related? Again, I have never spotted before. Also, my boobs have been extremely painful and have never been before.