What might lead to pain in lower stomach left side?

Many possibilities.: Causes of left lower abdominal pain can include but are not limited to: ovarian cyst, ectopic pregnancy, diverticulitis, endometriosis, inguinal hernia, ovulation pain, intestinal obstruction, crohn’s disease, abscess, ulcerative colitis, seminal vesicle inflammation, cancer, aortic aneurysm, renal infection or stone or injury. Get chronic pain checked especially if associated with stool changes.