A cut on the thigh wouldn't make you more susceptible to herpes, I would think. Your various symptoms, as you realize yourself, are from anxiety and fear. If you contracted herpes from that episode, you would have blisters, fever, and swollen glands. If you friend has herpes (I assume you mean genital herpes), then you might have contracted it, but if her herpes was inactive at the time, the risk from a single contact is low. You are correct to get a blood test. Assuming it's negative (a safe assumption, I think), just be sure it's been long enough after the exposure to rely on--some tests don't covert for 3-6 months. Check with your doctor and lab. Meantime, all this reading and worrying is doing you no good.
Best.
Dr. Rockoff