I think i was exposed to oral herpes, and my neck as an itch is that a sign of oral herpes?

Usually not: Oral herpes lesions are seen on the lips and inside the mouth or what we call you mucosal surfaces. They are not going to cause itching in your neck.

Perhaps: It could be herpes, a contact allergy to her makeup, a mechanical irritation to the skin either related to sex or anything that happened to your neck before or afterwards. See a dermatologist for diagnosis. Herpes simplex virus usually requires a break in the skin to cause an infection in the skin.