Two bits:
1. It doesn't matter how long you've been with someone, if you've had previous partners.
2. It doesn't matter how long they've been with YOU, if they've had previous partners.
3. Sleeping around isn't required for contracting an STD. Pathogens don't care whether you're a prostitute or having sex for the first time on your wedding night.
That said, a pimple looks absolutely nothing like herpes, so it'd be silly to think that's what it is.
_________________
"Such is the Frailty
of the human Heart, that very few Men, who have no Property, have any Judgment of their own.
They talk and vote as they are directed by Some Man of Property, who has attached their Minds
to his Interest."