What Causes Delayed Periods Along With Abdominal Cramping And Vaginal Spotting?

I just took a pregnancy test and it came out positive. I'm 8 days late on my period and have been cramping and spotting for the last 10 days. The spotting color has gone from redisj pink to dark brown back to light red. It's not heavy at all. But I just used the bathroom and I saw light colored flakes at the bottom of the toliet? What is causing the flakes?