I need help with aim ?!! PLEASE.?

OHMYGOSH. someone liked hacked my freaakin' aim and keeps sending everyone on aim these random links like, "did you see my new pix? something.blahblah.com". and then everyone ims me back saying what is it ? and it bother me SOOOOO bad ! what happened ?! how do i fix it ?! it's not cohs of the version because i use aim express and meebo sometimes. SOMEONE PLEASE HELP ME.