Hemorrhoids don't necessarily itch but they also wouldn't be in your perennial area and wouldn't remain there nonstop for years. They'd be about your anus. I'd see a doctor again and stress it has grown and it is painful and you are very concerned. Mention the change in bowel movements and the constant urge to go. The constant urge does sound somewhat consistent with a hemorrhoid because you hurt so you don't end up being able to finish, but if it is, you'll need to work on not straining during a bowel movement.