I Haven't Had Sexual Contact Of Any Kind In Nearly

I haven't had sexual contact of any kind in nearly 3 years. I recently developed blisters down there. with out doing a swab the dr I saw said it was herpes. however, herpes has a 3 week incubation period. It has been nearly 3 years. Herpes blisters from in a cluster. this didn't. herpes is supposed to be painful or itchy. this wasn't. what else could it be?