Hello,
Thank you for your post.
It is very difficult to know what this could be without a proper examination. However from your description, it does not seem likely to be related to syphilis or any other STI. Your symptoms are most likely to be consitent with folliculitis or a simple skin infection, and not anything transmitted sexually. The type or rash described, the location, and the timing are not typical of syphilis.
I hope this helps.
Best wishes,
Dr José
To clarify, I didn't have any sexual relations for 80 days before the "pimples" came about.