you mean the lower left side of the abdomen...like where the sigmoid would be?
Are you female...could be ovulation? I think I asked you that before, can't remember.
Low in the rectum inflammation can cause more discomfort...especially if the stool is more formed going through the colon. Especially if there's some gas.
Are you using any rectal meds?
Could also be nerve related from sitting in tight pants or pressure of underwear or just plain old back pain radiated down a nerve in that area. Does it go down the inside of your leg as well?
Have you been exercising, dancing or walking lately?
quincy