redirecting to url that will never complate
The biggest issue is that the query string should be passed in separate from the base URL itself, eg, it should be part of the $options array argument to drupal_goto().  Otherwise, as you've noticed, drupal_goto() doubles up a lot of times.  If you fix that, I am fairly confident that you will get it to work.

Check out http://api.drupal.org/api/drupal/includes!common.inc/function/drupal_goto/7
and
http://api.drupal.org/api/drupal/includes%21common.inc/function/url/7 
for more information on this.