issue with generating links from database in PHP - php

Question

First of all, I will try and keep this as simple as possible.
This is part of a larger script that generates a breadcrumb link list depending on which category the user is currently in on the page.
Something like:
Hats > Mens > Green
Each of the categories also have their corresponding links so the user can click back on it.
The problem I'm having is that for some reason, I'm getting an additional link inserted that is the current category, right before the top category.
For example, the output, should be:
<b>Category:</b>
Hats >
Mens >
Green
But I am getting this:
<b>Category:</b>
Hats >
<a href="categories.php?parent_id=175828&name=Green&keywords_search=" title="">
Mens >
Green
</a>
Note that the difference is that the current category link (but without the name) gets inserted almost at the very top again, in addition to an additional link closing tag at the very end as well.
What could be the problem? I've spent nearly 6 hours on this and can't figure it out, so I'd really appreciate it if someone could tell me what is wrong. Maybe I spent too much looking at this and am "stuck inside the box" :)
function category_navigator ($parent_id, $show_links = true, $show_category = true, $page_link = null, $additional_vars = null, $none_msg = null, $reverse_categories = false)
{
global $reverse_category_lang, $category_lang, $db;
(string) $display_output = NULL;
(int) $counter = 0;
$none_msg = ($none_msg) ? $none_msg : GMSG_ALL_CATEGORIES;
$page_link = ($page_link) ? $page_link : $_SERVER['PHP_SELF'];
if($parent_id > 0)
{
$root_id = $parent_id;
while ($root_id > 0)
{
$row_category = $db->get_sql_row("SELECT category_id, name, parent_id, hover_title FROM
" . DB_PREFIX . (($reverse_categories) ? 'reverse_categories' : 'categories') . " WHERE
category_id=" . $root_id . " LIMIT 0,1");
if($counter == 0)
{
$display_output = ($reverse_categories) ? $reverse_category_lang[$row_category['category_id']] : $category_lang[$row_category['category_id']];
$display_output = (!empty($display_output)) ? $display_output : $row_category['name'];
$ace = $row_category['category_id'];
$acename = $row_category['name'];
}
else if($parent_id != $root_id)
{
$hover = $db->get_sql_field("SELECT hover_title FROM " . DB_PREFIX . "categories WHERE category_id='".$ace."'","hover_title");
$category_name = ($reverse_categories) ? $reverse_category_lang[$row_category['category_id']] : $category_lang[$row_category['category_id']];
$category_name = (!empty($category_name)) ? $category_name : $row_category['name'];
$display_output = (($show_links) ? '<a href="' . $page_link . '?parent_id=' . $row_category['category_id']
. '&name=' . $category_name . ((!empty($additional_vars)) ? ('&' . $additional_vars) : '')
. '" title="'.$row_category['hover_title'].'">' : '') . $category_name . (($show_links) ? '</a>' : '</a>')
. ' > <a href="'. $page_link . '?parent_id=' . $ace . '&name=' . $acename . ((!empty($additional_vars)) ? ('&' . $additional_vars) : '')
. '" title="'.$hover.'">' . $display_output . '</a>';
}
}
$counter++;
$root_id = $row_category['parent_id'];
}
$display_output = (($show_links && $show_category) ? '<b>Category:</b>' : '') . $display_output;
}
$display_output = (empty($display_output)) ? $none_msg : $display_output;
return $display_output;
}