Pain on left side of pelvis ?

Check it out: Soft tissue causes = constipation, diverticulitis, colon cancer, cyst/tumor of ovary/uterus, low kidney stone. Bone causes = hip arthritis, micro fractures from osteoporosis, nerve pinch/arthritis of lower spine, bone tumors. If it doesn't resolve with a good poo, or is ever associated with fever, bloody urine/stool, vaginal discharge, or is persistent/worsening, seek medical help.

See Specialist: Consider imaging studies for your spine if you believe your pain is sciatica or sacra-iliac in origin. Pelvic congestion syndrome can mimic sciatica occasionally but it is typically a diagnosis of exclusion, meaning everything else has been ruled out first.