If the symptoms of inflammation of the posterior urethra are diagnosed, it is recommended to take diclofenac sodium capsule orally for three days. If you are diagnosed with bladder or posterior urethral stones, you will need to undergo extracorporeal shock wave lithotripsy or urethroscopic cystoscopic stone lithotripsy and stone extraction surgery to relieve the pain. 3, if you are diagnosed with prostatitis causing pain in the posterior urethra or causing pain at the end of urination, you are advised to take oral prostate relief capsules. The actual pain can be relieved by a cystoscopy and surgery.