What Causes Burning During Urination And Fishy Smell?

hello i am a 17 year old girl. my wieght is 154 my problem is that it burns when i pee and after i do it still feels like i need to use the restroom again.i also have had this fishy smell. but its only started today. and ive never had sex i dont know what wrong..is it possible i have an STD?