MSF, ya got it right mate. CS is the only thing that really works but it takes about 5 minutes of honking and snotting to get those sinuses sparkling clean.
Alternatively.....
A sachet of Beags' Hot Turbo GINGER Sinus Scourer
3 Soluble Aspirin
Juice of one lemon/lime and toss in the skin for effect
Crushed/grated ginger
Half a teaspoon of Tea Masala
3 Tbsp Honey
3 tots Buchu Brandy (You can use whisk(e)y at a pinch but it doesn't have the hallucinogenic properties of Buchu)
All this in a pint mug and top up with boiling water.
When the bedclothes stop telling you to stuff Aunt Agnes with treacle and roast her in the neighbours' lounge you should be feeling a bit better.