--you might need some imaging or close orthopedic examination of the pelvic area there; certainly compressive neuropathies can come from the lower spine, but also from the hip area and also from the knee.

Given you description of symptoms, there may be an impingement of nerve as it passes through the lower pelvic area on its way down the leg--and yes, this is more common in people who are overweight.

NERVE ENTRAPMENT IN THE HIP REGION: CURRENT CONCEPTS REVIEW