I describe sinusitis as being like I've been hit across the face with a baseball bat.
If that strikes a chord with you, I suggest dealing with it aggressively -
Sudafed from the chemist. Psuedoephedrine, to be precise (the stuff you can buy from the supermarket/off the shelf is crap). Don't worry about getting extra painkillers and caffeine in with it - it's cheaper to take the single pill + 29p paracetamol with a coffee.
Cooled, boiled water with salt/a pinch of bicarb/special mixes to physically shift the gunk. A neti pot is perfect, especially as they generally come with premixed packets of powdered salt and bicarb, but sometimes needs must and you have to make do with a jug or a toy teapot. It feels foul to put your head on one side and tip warm water up your nose until it comes out the other side, massaging the sinuses (eyebrow, under your eye and just above your front teeth) until more than a tiny tickle of water comes out, but it works.
I know people often say steam, but I find, when the sinuses are so swollen and painful, the last thing I need is to add more warmth and increase the blood supply to an already inflamed area - part of the blocking is the blood vessels already swollen.
And cold packs. Lots of cold packs.
This gets the swelling down if only temporarily, you get as much gunk out as possible, the pain reduces.
I sympathise totally. The first sinus infection I got was in the lower sinus and I thought I was dying of a dental abscess. Turns out that dental abscesses are small fry compared to a slightly blocked sinus, as I've had those and barely noticed the discomfort - the sinus had me hitting my face in my pillow and wishing for death.