Acire26

The first day of my last period was 9/21/09. I had unprotected sex (did not pull out) on 10/16/09. My cycle has been consistently 33 days since 06/09. I expected my period on 10/24/09. For the past three weeks I have felt nauseous (no vomiting), gassy, constipated, bloated, really hungry and exhausted in the afternoons. I also have slight cramping feelings on both sides of my tummy as well as tender breasts. I took a pregnancy test yesterday and it was negative. I am 26 now and have not missed a period since my first one when I was 11 yrs old. I have not been more stressed than normal. What is going on? A friend of mine mentioned Pelvic Inflammatory Disease as a possible cause for my missed period.