What's going on ?

I was recently 2 weeks late , I took a test , negative . Next morning , I started bleeding heavily . Now 3rd day on my period and I'm almost completely done with my period (my period usually lasts about 6-7 days ) . I've been dizzy , cramping , bloated , tired , etc . I had sex about 3 days before I 'started' . What could be going on ? Is this normal , or should I test again in a few days ?