Hello, i had unprotected sex-am a male-with a woman 6 days ago. this was my first partner in 7 years and previously only had one partner. about 4 1/2 days later i noticed a red rash (slightly raised) near the base of my penile shaft. it still remain

Probably not an STD: No STD causes this sort of rash or in this location. If primarily blisters that become pimples then open sores or scab-covered, herpes would be a concern. But this sounds more like physical irritation, allergy (e.g. vaginal hygiene product), or a superficial non-STD skin infection, e.g. fungal. It doesn't sound worrisome, but if it continues or you remain concerned, see a doctor. Good luck!