Here is a problem ...

The reference for the categories_id changes depending on how you move around the Catalog ...

Toss this in the file just to see how these variables move about:
echo 'PATH ' . $_GET['categories_id'] . ' - cpath ' . $_GET['cPath'] . ' - get $current ' . $_GET['current_categories_id'] . ' $current ' . $current_categories_id . '<br>';


You can code for which of these is available to use as the:
'&categories_id=' . $something

You just need to write something to make the $something correct for more than one click ... easy smeazy, eh?