I sometimes have sudden onset testicular pain and tenderness that last only for 5-10 minutes and testicle draws up. but ultrasound normal. confused?

Cremaster muscle: This attaches to testicle ; contraction will pull up testicle ; tend to cause twisting of spermatic cord like intermittent testis torsion. Ultrasound, when not in pain, will always be normal. Can be corrected by surgical division of cremaster muscle ;/or scrotal fixation of testis.U can check yourself by twisting affected testicle round ; round like closing book ;c if this exactly duplicates pain.