If your pregnancy test is negative, it doesn’t seems that you are pregnant. Lack of a menstrual period can be due to the presences of a functional ovarian cyst, for example. You can request a blood pregnancy test (beta) to exclude pregnancy for sure. A vaginal ultrasound examination will be necessary to confirm or exclude the possibility of an ovarian cyst. Cramping and diarrhea can be caused by an intestinal infection. You can see your gynecologist for the missed period and your GP (general practitioner) for cramps and diarrhea.