Causes of itchy urethra?

I am 20 years old, male, had first sexual contact ever about 2 weeks ago. In these past two weeks, me and my girlfriend have been having sex once or twice a day, vaginal intercourse and oral sex. We did not use any form of protection.

In the past 2-3 days, I have been experiencing almost constant itchiness in my urethra, with infrequent mild pain, especially at the tip. I have also been noticing a small amount of mild-smelling pale yellow fluid (not smelling of urine) coming out of the urethra, pretty much any time I take off my underwear. I previously ignored that fluid as it smelled like remnants of her own vaginal fluids on my penis, even though I showered and cleaned properly after each session. Today especially, the itchiness isn't unbearable, but it's causing huge discomfort and the only thing I can think about.

Since I was a virgin before (please forgive me if I sound naive!), I pretty much come with a clean bill of health...but I know she's been with other guys...I assumed she was safe otherwise she would have insisted on a condom :S

I'm incredibly worried as I am in foreign country where medical assistance is hard to come by, and sympathetic English-speaking doctors are not really a dime a dozen!

I pray that I don't have an STD, could it be anything else?

I am also upset as I feel it compromises our own relationship, if she knew she had an STD and didn't tell me.

I would really appreciate your prompt responses and suggestions on this matter.

Thank you!