I usually have normal periods that last 5-7 days. For the past 8 months or more, i've had a lot of pain in my lower abdomen/cervical area, sometimes it feels like something is exploding inside me. About 5 months ago I went to the doctor and they did an internal sonogram and found nothing. I still have pain in my cervical area along with almost constant pain in my left hip and occasional pain on the right side of my lower back. For the past 3 months my periods have only lasted 2 days. This month, it lasted a day and was dark black and clotty. I took a pregnancy test just to rule that out, it was negative. I am 20 years old and in otherwise good health condition.