I've posted this before, but from a chronic (no more) sinus person...the shower snot is a saver. (I know it's gross, but you can always clean the shower.) You might puke the first time or two, but it really does clear you out. Just imagine swimming under water and inhaling all that water. Eww. But, it works.
Nice hot shower...**** it in through your nose and blow it out. Do that a couple of times and it clears you to a point where you can actually breathe and release the tension and headache.
I used to have severe sinus infections that went nearly back to back. That was 15 years ago. A doctor suggested this technique and it has worked wonders. As SOON as I feel that pressure, I do it and haven't had a sinus infection since. It has worked wonders. I was facing surgery through the upper palate and top of the nose. I'll gag a bit to not go through that.
Hope you get to feeling better.
Abbey