Can you try the brand, or the generic, of Mucinex? I find that it works really well. It will target just the sinus crap. If you have chest congestion, the Mucinex (or generic) with the expectorant (guaifenesin) works really well.

Here's the website, just ignore the video cause the "mr. mucus" guy is obnoxious. I do use the generic of Mucinex and it works really well.
Mucinex website