When you changed your password(s), did you make them difficult to hack? The most difficult passwords are a mix of letters and symbols, especially if you put symbols in the middle. A good way to make one that you can remember is to use numbers that look like letters in the middle of words.
Also, did you change your security questions to something that would be difficult for most people to figure out or find out, even people who know you and have lived with you (like old roommates, etc)? Not that it's likely for anyone you know to do it, but if it's info your roommates don't know, it's probably also difficult to find that info anywhere on the internet or in your old paper mail that you threw away.
I would recommend changing your passwords and your security questions right away, don't email that info to anyone, and pick difficult passwords and security questions, but make them so that you can remember them.
Also, turn off all of those automatic password fillers on all of your computers, turn off the auto blank fillers, and turn off the stay logged in features on all of your computers including your cell phone. Sign in yourself every time.
Oh yeah, and clean out all of the cookies and junk on all of your computers to clear out absolutely all possible records of your passwords.
I know it's a pain in the ass, but it's worth it. I had a hacker last year that I couldn't get rid of until I did all of the above. Then I finally got rid of him. Hasta la vista, baby!!! (sp?)