Pain in the lower back can be of various origins, Ur symptoms suggest it can be PID, Prolapse Intervertebral disc in Lumbar spine. Try to do some sciatic nerve glide exercise, avoid a lot of stretching or strengthening exercises initially, use hot pack at your low back and right buttock.
Next Steps
Visit a Musculoskeletal Physiotherapist
Health Tips
Avoid carrying heavy weights, DO NOT CROSS YOUR LEGS WHILE SITTING