So let me ask you : have you ever had a cold sore on your lip or in your nose? If the answer is yes, then you already have HSV 1 which is what you would get from receiving oral sex from this person. So you wouldn’t get it genitally, in all likelihood
1. Without any sores, I am less likely to think that this is herpes, by itself. Most people with genital herpes do get sores. The red areas turn into blisters, then open, then scab.
2. Itchy thighs and buttocks, especially in the winter, do not concern me at all. the little red bumps are something most everyone, particularly men get, on their skin in these areas.
3. This doesn’t sound like herpes to me either
4. Sciatica pain is common in the US, but mostly from back issues as people age. This, even in combination with your other vague symptoms, does not sound like herpes.
There are certainly bacterial and fungal issues that can cause redness of the genital skin. Weather can cause itching skin in the winter, back issues can cause sciatica. The chance that you would acquire herpes at a single encounter statistically is low. You symptom timing is way off for herpes as well – the majority of people who get herpes do so within 2-10 days with the average days to symptoms from infection is 5.5 days. You are well out of that.
So my answer would be probably not herpes, but I can’t be certain.