Hi. Thanks for your query. Noted your history of sudden testicular pain, normal blood and urine tests. Radiculopathy at lower lumbar and S1 ca not cause this. It is possible that there is a local problem like orchitis, epididymitis, partial torsion, varicolcele and so on. Hence the investigations of choice is ultrasonography of the scrotum with color doppler study. Consult an Urologist or a General Surgeon. He would evaluate you clinically with proper examination and plan for further investigations and treatment.