What Causes Stomach Cramps Along With Headaches And Spotting?

Just wondering what other issues other than pregnancy could be going on with me. I am 3 weeks late, 3 negative pregnancy test, I did have spotting about a week and a half before my missed period. Right now I have stomach cramps, frequent headaches, bloating, nausea with random vomiting, constipation, tender nipples not breast, acne breakout (which could have been considered more of a rash), and sleeping more than usual. Last month during my last period I was moving, eating habits changed, and a little stressed but took a vacation and very comfortable now that I am settled in and above all I crave bananas (I hate bananas!).