15 dpo creamy yellowish cm

AF due yesterday but hasn't shown yet, so I tested and got BFN. I had cramps 8 dpo and I've had cramping the past two days and today so I put in a tampon before work this morning figuring af would show. I just took it out and it was covered in this very thick, creamy yellowish white cm. 
What the heck is that about? My cm has never been anything but white or clear. No smell/infection