What Relieves The Pain In Penis Caused After An Oral Sex?

Hello Doctor, I am a 21 year old male and my girlfriend did oral sex. While performing the act, she bit my penis. It hurts a lot but I am not bleeding. From a scale or 1 to 10, its a 10, thats how bad it hurts. Its hard for me to pee as well because it stings. What can I do to get my penis back to normal and to ease the pain? what kind of antibiotics can i buy?