Hi! After Urination, And A Bowel Movements, I Have A

Hi! After urination, and a bowel movements, I have a few more drops of urine come out and it feels like someone suddenly shoved a red hot fire poker out of my urethra. The pain nearly knocks me to my knees! I have been tested, and have no UTI or STDS, and full blood panel, CBC, all normal. I'm not sexually active, and don't have a yeast infection either. Any ideas? I'm so sick of this horrible pain! Thank you!