Late, please help

So my last period was August 18th and I haven't had a period since then. I have been spotting for a couple of days and took a pregnancy test last night that came back negative? I can usually tell when I am close to starting because I just feel awful and start cramping before but I have no symptoms of my period coming any time soon. What does this mean? Should I take another test? If so how long should I wait? Please helppp.