Advice- AF vs implantation

Ok so AF is due today I'm not always bang to the day but when I AF arrives it's usually in the night and full on straight away. Using the average cycle I should be due on today. Friday I had two tiny spots of blood I never spot and yesterday just once I had blood when I wiped but it wasn't like the start of a period it was light pink fresh blood abit but not masses. I am really crampy but no AF. Thoughts . . . .