What Causes Pain In Penis After Ejaculation?

Everytime i ejaculate, i get an aching pain in the end of myEverytime i ejaculate, i get an aching pain in the end of my penis shortly afterwards for about an hour. Its not particularly painful. Just uncomfortable. I get the odd twinge at the end of my Penis when im not ejaculating or urinating. Its not painful at all when i urinate. I just get an unpleasant, dull aching shortly after i ejaculate. Nowhere else hurts when this happens. Can u help me?