Possibly pregnant even after period?

Okay so My period was a little bit different than normal. I just ended it two days ago but it was a lot less red than normal, more brownish and tapered off a lot quicker than usual. today I feel so nauseous and gross i dont know whats going on. I have weird twinges in my uterus today and yesterday. I have been extremely tired. What is going on?!! Has anyone experienced this???