I'm sorry I should have been more clear - the recurrence was on the labia only. But regardless it sounds likes I should go ahead and get the blood test - thanks for your help.
From your description I am skeptical you have herpes. Initial herpes rarely involves the buttocks. The virus has to be "massaged" into the skin, and the lesions occur exatly where that happens--in other words, the genitals or anus, usually where sexual friction is greatest: mostly the vaginal opening and labia minor in women, the penis in men. I have never seen a case in which the initial infection was manifested primarily on the buttocks, even though recurrent outbreaks can happen there.
As to the second "outbreak", that also doesn't fit. Recurrent herpes is always localized to one side of the body's midline, and typically very localized--generally in a small patch no more than 1-2 inches in diameter. Lesions on both buttocks is unlikely to be recurrent herpes. Anyway, although recurrent outbreaks can involve the buttocks, upper thighs, etc, that occurs in no more than 5% of infected people; 95% of recurrences are genital or anal.
The negative PCR or culture doesn't help much one way or the other. Even in herpes, those tests can miss the virus, especially if the lesions are healing when the specimen is collected.
Therefore, I agree with your tentative self-recommendation: Have the blood test. You are correct that a positive HSV-1 result won't mean anything one way or the other. But the HSV-2 result will be the important one. If negative, you can be confident you don't have genital herpes after all.
Good luck-- HHH, MD