1)Spammers are using your email address (spoofed more than likely) to get past the spam filters. You can either cancel the account or you can wait it out and eventually (like a month or two) they will move on to another name.
2) scan your computer ASAP
3) Change your password, security question and answer from another pc, if this isnt possible, use an on screen keyboard. Its likely you have malware on your computer.