I Have Had A Dark Purplish Bluish Patch On My

I have had a dark purplish bluish patch on my scrotum for 40 years. I never really though about it until my wife mentioned it again recently. I do get jock itch but this doesn't itch or change size or color. As far as I know the only std I have had is herpes but no outbreaks for 20 years. I also had 2 viral warts removed around 20 years ago. Could I have had some other std that has gone into hiding and left it's mark behind? I'm afraid I can't afford to see a specialist. Thanks