Please, I am getting crazy with the pagination class :(

[eluser]Althalos[/eluser]
I would suggest opting for a URL like this: example.com/articles/page/2/user/username

And then in your controller, put this:
$uri = $this->uri->uri_to_assoc(2);
echo $uri['page']; //Echos "2"
echo $uri['user']; //Echo "username"