Itchy scrotum for 3 years

I have had an itchy scrotum for 3 years.I have seen doctors several times and throughout this period i have been using Surfaz-SN cream and some antibiotics e.g Griseofulvin. After a week of treatment, the itch goes but comes back after a week or two. I make sure to use the cream till it finishes.The itch comes on and off and sometimes the scrotum becomes reddish and shiny.I would be grateful if anyone could suggest a more effective treatment.I am 30 years old