Hurts while i pee, pain and discomfort after urination. tested negative for std, uti, diabetes at the er. what else could cause these symptoms? thanks

Urethritis: Many reasons including minor local urethral trauma from several reasons, including tight underwear, autoimmune disorder that may need more investigation, small kidney stones, or rarely, distal urethral obstructions. Suggest you see a urologist and have exam with some urine and blood tests if pain persisting, may need ultrasound or other tests if pain source unclear