Well, a strong ginger tisane always helps my girlfriend get over sinus headaches... I keep my dorm well-stocked when allergy season rolls around. So maybe that would work?
Also, I recommend making a tisane out of the following ingredients: hot water, lemon juice, peppercorns, ginger, cayenne, and a lot of honey. It's very spicy but that and the steam clear the sinuses right up! I used to drink this all the time when I was little (I had really bad ear/nose/throat issues). Sugar can be added to taste.