First, I don't think it was an STD. Herpes looks nothing like what you describe. If I had to guess, I would say it was either a bacterial infection, or else you just got irritated and anxious and scratched it to the point it left marks. Any irritation can leave long-lasting dark marks on the shins.
As to what you have now, it's probably a form of eczema, and certainly not related to a long-ago sexual encounter.
My advice is to see a doctor and get a specific diagnosis and treatment. If I understand you to say that you were with the girl you mention several years ago, it may not be possible to say with certainty what the rash was, but again, an STD seems most unlikely.
Best.
Dr. Rockoff
I doubt that the current problem with the hands is connected, that that's just my guess. Good luck.
Can you please respond to my last post?
Thanks.