What Causes Cramps Like Left-sided Pain In Abdomen?

My Monthly cycle just ended and starting last night I ve been having sharp cramp like pains on my left lower abdomen about 2 inches or so from my left hip bone. It painful to the point, would wake when I would turn or move in my sleep and I wasn t able to get up normally and had to roll out of bed. I ve taken an Aleve this morning, it seemed to subside to where I could function normally, but still with pain, not it is back. I thought it might be my appendix, but the MyWebMD website said my appendix is on the right, not left side.