I Am 17 Years Old With No Sexual Experiece. About

I am 17 years old with no sexual experiece. About a week ago i felt a strange pinching feeling on the tip of my penis. Later i looked T it and it was very red and somewhat swollen on one side of my urethra. It sometimesdoesnt hurt that much, but at other times i get extreme pain from it. Ow can i treat this and how was it caused. Thank you for your time