HELP!

Okay so I for the past week or so I have been nauseous every day, I have like no appetite, I am constipated and have really bad gas. I'm crazy tired and my legs feel sore. I have a little cramping and some headaches and get hot randomly. I took a pregnancy test and it came back negative but I'm not sure with all these symptoms. (I haven't missed a period yet but I should have started yesterday). What do you guys think?