Post count within tags TDO Tag fixes

OK so I’m looking for some help.

I’m running a copy of WP, with posts organised by category, then using the TDO Tag Fixes plugin I further filter those category pages by tag.

Just for clarification, the URL structure of the site follows this format:

https://example.com/category/
https://example.com/category/?tag=tagname

To link through to those tag sections, I’ve created some icons – the HTML format for each of these is currently as follows:

<a href="https://example.com.com/<?php echo get_category(get_query_var('cat'))->slug; ?>?tag=tagname" class="tagname_icon">
			<span>
				Arts & Crafts
			</span>
		</a>

This is where it gets a little tricky.

What I’d like to do, is check the number of posts matching both the category & tag filtering, then add a specific class to the link if there are more than 0 posts.

I thought I could use query_posts(‘tag=tagname’); to do this, but I can’t use that to filter by both category & tag – so basically, I don’t know what to do from here.

Not sure if this should go in WP-Advanced or not? Anyway, I’d appreciate any help you can provide.