Shortcode in a custom post in custom query

Hi everyone!

I have a custom shortcode that works perfect in default page template but I have a custom page template with a custom query:

$loop = new WP_Query( $args );
	while ( $loop->have_posts() ) : $loop->the_post();
	...
	endwhile;

I know about the function do_shortcode:
echo do_shortcode( '[shortcode foo="inscript"]' );

But the problem is that I cannot pass that foo parameter/variable from the page visual/text editor. That foo parameter can be only retrieved from my custom php file as above.

I can replace the query with the default query:

while ( have_posts() ) : the_post();
...
endwhile;

but that breaks everything because I am using a custom theme.

I will appreciate any advice – also where I might be looking into more.