|Listen to your doctor and get tested for STD and STI, if that's not what it is, could be an infection like yeast infection , urinary infection. Get treated right away in case its a veneral disease. Has your girlfriend had sex with anyone else. Use condoms now everytime. Disease and pregnancy prevention everytime.
Hi and welcome. you might want to post this on the STD forum as is specific. A first symptom of STD's would be a white/yellow discharge that usually appears about 5 days after exposure. With out this it could be a simple urinary track infection. Sounds like no big thing and is good your going for a checkup. Make sure you follow up with your appointment.