Thanks for posting your query at DoctorSPring.com
I can understand your concern.
You are not the cause of the breakout. It could be a bout of folliculitis which is a bacterial infection of the skin.
The treatment for it would be application of mupirocin cream twice a day for two weeks.
It doesn't seem to be directly related to having a sexual intercourse.
You could send me a picture of the breakout to confirm the diagnosis as to what it really is.
Please let me know if you have any queries.