Welcome and thanks for posting your query to HCM.
Let me reassure you first that your rash and symptoms are not related to any sort of HIV
infection to say it boldly (which you are not able to ask).
After reading your query it appears that you are quite worried about the possibility of HIV infection and its manifestation as a rash in yourself after the intercourse.
The best thing in your part of exposure was wearing a condom which provides you the best protection. Even if we think of possible exposure then the symptoms you are experiencing are very early. In HIV the symptoms appears after about 8-12 weeks of exposure.
So do take care of simple viral rash
and do not take much stress
With good health wishes
Dr. Sanjay Kumar Kanodia