Herpes can be up in the pubic hair area...I think that's what you described. The way you described it sounds like a herpes lesion but of course it could be something else but I can't say to you "no it sounds nothing like herpes". Does this sore ooze clear puss...another sign. Remember or I should say "know" that herpes that we call Cold Sores can be transmitted to the genitals giving someone genital herpes and there doesn't even have to be a sore present on the mouth to spread it to genitals through oral sex. And another sad truth is that herpes isn't usually something that is tested for when you have an STD test done at a clinic. Syphilis, Gonorrhea and HIV are the common tests done and most likely if you didn't ask for a herpes blood test you probably didn't get one. It could very well just be an ingrown hair though. But keep an eye on him and see if this condition comes back or if it lasts longer than the normal ingrown hair(suspicious). Suggest to go to a clinic and ask to both be tested for herpes type 1 and 2.