Sudden irritation and the swelling and redness on penis

2 days ago i noticed that i had itching on my penis. i later that day found a small red shiny pimple. The next day it became painful and no longer itchy. i looked again and saw the area spread. It is all underneath on the skin and shaft. Now there i a bigger area about 2cm radius which is shiny and has the same pimple looking things accompanied by a sticky fluid which i am guessing is puss. It still hurts and plan on going to the doctor but i want to know is it serious like genital warts or is it something that will eventually fade away because it is bothering both me and my girlfriend. The weird thing is that i haven't had intercourse with anyone else but my girlfriend who is fine.