I'm 13, and think i may be pregnant.?

Okay, I'm 13, Me and my ex. had "intercourse" about a week ago, and I've been Really Tired lately, I've been having unusual sharp pains in my stomach, my lower back hurts and my "boobs" have been sore, Only a few friends know, I should have my period around the 1st-5th, And i know your probably saying "what a whore or a slut" but I'm really not, He sorta pressured me into it, And i wish wouldn't have done it. My parents don't know either, and I'm not sure what to do, Please Help.