Suggest Treatment For Rigworm In The Groin Area

I am 66 years old and never had a problem with ringworm in the groin area unil 6 years ago. It keeps reacurring and the only thing that works is Lamisil and then it takes about two weeks to completely get rid if it. And then I keep using the lamisil cream for a total of four weeks. But then invariably it always comes back.