Caught by a Scammer

well someone tried too scam me i dont know how he got my password but he logged in on my account and i changed the password and everything he cant log in in game but he bought 20 m16a2's with my account and other stuff so he is still logged in on the forum with my account he kicked everybody out of my clan and changed the clan introduction too we are hackers and changed my forum name 2 iam_scamer can someone tell me what i have too do now becuz if i buy zp i think hes gonna buy useless stuff with it and i dont understand when i change my password why doesnt he get logged off automaticly hes logged in in this site right now with my old password thats not good man tell me what i can do please and im sorry if i dropped this at the wrong section i just need some help with this one so i can do what i have too do.