Hi everyone, I'm Duchess, 28 years old. My last period was July 28,2017. I'm expecting period this August 28,2017 but…

Hi everyone, I'm Duchess, 28 years old. My last period was July 28,2017. I'm expecting period this August 28,2017 but it's already September 3. 1st day of September night, I felt slight dizziness and uncomfortable feeling of my stomach and the day after that . Now I felt a slight headache and cramps in my ovary but still no period. I had unsafe sex few days before my last period(widthrawal). I took pregnancy test last September 1but negative. I'm not sure if I'm pregnant. I'm having slight dizziness and uncomfortable feeling of my stomach and slight headache and cramps. So I wonder. Any advice? Thank you and God bless