I had my period on march 18th n ended march 22. That night I had unprotected sex and my bfs precum was inside me but he pulled out when he cummed. Then on the 25th I had sex again, since then I've been feeling nauseous , dizzy, headaches , lower back sore. I went to my OBGYN march 30 n took a test and it was neg my OB SAID ITS STILL TOO EARLY TO TELL IF I'M PREGNANT OR NOT. Today april 1st I woke up feeling sick to my stomah tried to eat thinking it would help felt worse, I started having cramps but my period isn't due till the 15th.. what could it be please help.