Sounds like someone has logged in. Did you sign in or do something from an email you received that updated it. Did you file anything recently? If you haven't done anything, you might want to change your password. It can be likely someone is hacking your account, which could give them access to your social security numbers and other personal information you might have stored there. Highly recommend changing password and monitoring for any signs of identity theft for awhile if you have no idea where the account activity is coming from.