when do you have a implantation dip?

I'm know it's ok if my BBT does go up and down but it can't go below the cover line. My breast hurt more today then they have I'm very bloated and having cramps. I've been getting headaches and I do feel like I do want to eat more though out the day! My CM is creamy. Can this be implantation dip?! 
 s BBT chart still looking ok!!