Hi,
Since it's apparent your site was compromised, given odd users were added without your permission, I recommend you try the following steps:
1. Change all administrator accounts to "editor" and leave only your account in place.
2. Change your admin password.
3. Change your FTP password. Pic: http://goo.gl/v5MFJF
4. Change your Godaddy password.
5. In WordPress, Click Dashboard -> Updates -> Reinstall Now button
Then report back here as to whether that helps your situation.