What actually causes my low back pain with no sciatica? I have an 8mm herniated disc at my L5-S1 level without any sciatica. Is my pain in my lower left back caused by my muscles being over-worked to keep my body in balance? I'm confused with my pain because I don't have any sciatica. I've had this pain for years and the past 8 months it has greatly increased. I don't know how I get muscular pain as a result of the herniated disc.