one of my testicles is swollen, very sensitive, and painful when touched. there are no lumps. two days ago i suddenly noticed a sharp pain while I was seated which subsided after 10 minutes. Its been fine since but I can feel a constant discomfort while walking. I have had this condition for about a week now. I have read alot about testicular torsion etc and am a bit concerned, but I think the cause may be something simpler because normally I am not in severe pain. Three weeks ago I had a health check and that showed no STDs. What could be a possible cause and treatment?