Why am I getting cramps in the left side of my abdomen? I got my period 11 days ago.

Mittelschmerz. One possibility is mittelschmerz, or light cramping associated with ovulation. A small percentage of women can actually experience minor pain around the time of follicle rupture - typically 14 days prior to the beginning of the next period. This is simply one possibility among many and should only cause minor discomfort.
See your physician. Left lower quadrant abdominal cramps may be symptoms of diverticulitis, left ovarian cyst or twisting if the ovary, a abdominal hernia, a tumor of the abdominal wall muscle, an infection or just minor muscle spasms.