What Is The Treatment For Itchy Penis?

hi doc, last time i once a while when my penis feel itch which last a few day, will go off when i wash it everyday. But recently, it itchness stay on for long period of time. After every washing, i feel much better. But after say 6 to 8 hr later, the itchness came back again. there is no pain when i urint only internally feel itch. Is there some wrong with me?