Hi there Rob!
I note your history, delicate situation & your concern.
It is very possible that the symptoms you allude to are largely frictional or physical contact realted & not an STD
Having said that, online with the history supplied, no-one can tell you whether it is an STD or not.
Your best bet would be to go across to a Dermatologist/Venereologist nearest you @ ground0!
Alternatively, take good clear digital photographs & get back to me on this portal using the discreet 'Ask-A-Specialist' feature & Requesting for mois in person & we can take it from there.
A standard STD test kit will be available in any standard laboratory nearest you.
Cheers & wish you good luck & do Practice Safe Sex
Dr Praveen Rodrigues MD
Dermatologist & Venereologist