Your symptoms do not sound like herpes. They sound like irritation from friction. I don't know what relationship your girlfriend's symptoms have, if any, with yours. If I were you, I would apply a weak over-the-counter hydrocortisone (1/2% or 1%), clean the area gently, and see a doctor for definite diagnosis. The doctor can order a herpes blood test if needed, though your story does not sound like herpes, either this episode or the earlier one.
Best.
Dr. Rockoff