This is not herpes. I cannot clearly make out the rash you are referring to, everything seems normal here. There are some Fordyce's glands, which are normal clumps of sebaceous glands.
But if you have a rash, and this is after sexual exposure, you should have this checked out. Herpes is not there but other STI is possible.
Since you have a recent history of unprotected sexual exposure, this could be an STI, a sexually transmitted infection..
The common sexually transmitted infection which would produce symptoms like yours are:
Chlamydia, Neisseria gonorrhoeae, syphilis, Trichomonas vaginalis, etc.
You should now consult a doctor, you can also go to a STI/STD clinic.
You will need swab tests and blood and/or urine tests to determine your infection.
There are other possibilities like contact dermatitis, yeast infection, bacterial vaginosis, cervicitis, follicilutis, etc. These can be differentiated at the clinic if STI tests are negative.
For now, measures you should take are:
* Keep the area dry and clean.
* Avoid touching as far as possible. The point is to avoid bacterial infections.
* Wash with clean water and an antiseptic soap once daily and then pat the area dry.
But do go to a doctor or STD clinic/Planned Parenthood clinic at the earliest.