Wet, smelly penis with yellow discharge

Patient: I had sex for the first and only time 2 months ago and the girl has no STIs what-so-ever, however, I now have a yellow discharge from my penis and the tip is wet and smelly but there is no burning sensation. Now, I know I have no STI which leads me to the question: what is it?

Symptoms: Wet, smelly penis
Yellowish discharge