I've suffered from sinus allergy and infections my whole life, and really sympathize with you. I'd tried many things, and years ago I had a horrible attack, and went into a small shop in the mall selling vitamins and stuff. The clerk had recommended this squat little bottle of A. Vogel Allergy Relief, which is homeopathic, small tablets placed under the tongue, made in Switzerland. It works immediately on my itchy eyes, sneezing, burning, reddening ears from my sun allergy, and other allergy symptoms. I always slip a couple under my tongue when I go out to work in the yard, just in case. It was pretty pricey, but I've been getting it online for half that price ever since.
When A. Vogel came out with Sinus Relief, I got a bottle of it too, and while I haven't used it more than a couple of times, it did make my sinuses feel a lot better, and quickly.
I used a nasal syringe for awhile, to wash out infections, but then was given a bottle of XYLITOL Xlear nasal wash by a friend, and it does a better, less messy job. I get it online as well, and use it a few times a day or more.
I hope you find something that works for you.