I have not had my period since sept 15 and i took 3 pregnant test last month it was negative but i have cramps in pelvic area and a swolle abdomen?

Get checked: There are a number of reasons to miss a period for 3 months when a woman is not pregnant. The reason for no periods is lack of ovulation, and the cause can be hormones such as thyroid or prolactin are abnormal, or a condition called pcos, weight too high or too low, or stress. At any rate you will need an evaluation to find and treat the cause. Good luck.