Hello, I haven't been sexually active for 6 months until 3 weeks ago I have intercourse with my boyfriend. Two days later I started having a smelly yellowish discharge, I'm simply afraid it is some sort of std or infection that I'm not familiar with. What is it?

No one knows without examining you - sounds like some sort of sexually transmitted disease.

He wore a condom? You have both been tested for STDs? How recently?

Take a swab and send it to me. I'll send it to a lab, and they'll tell you what it is.

In other words, how do you think someone online will be able to diagnose what this is?

It could be an STD, it could be a yeast infection, it could be a different infection, there are literally hundreds of possibilities. Without testing it, there's no way to tell you what it is.

You'll need to see a doctor.

Dr. Alty - on another thread someone took a photo of "her vagina" in an attempt to obtain a diagnose. Could you diagnose from that?

Yellow discharge is a symptom of bacterial vaginosis or trichomoniasis. Only your doctor can tell you which one it is.