I supposedly had bad sinus and allergy problems too, but it turns out that through cleansing, I've cleared up my sinus issues. Here are some things I did - they may help you.
1. Grapefruit Seed Extract nose spray - a lot of my issue turned out to be yeast in the sinuses. Grapefruit-Seed-Extract is great for this and helps clear the sinuses.
2. Bowel cleansing - mucous in the sinuses is a sign of mucous build-up in the colon. Clean the colon and the body will flush out from the sinuses better.
3. Collodial silver drops in the nose - wonderful, natural antibotic. It has done so much to help my sinus issues that round after round of antibotics could not.
I put a 1/2 dropper full of collodial silver in my nose and hang over the side of the bed (upside down) to let it drain into the upper sinus cavitites.
4. Bear with me on this one. I know it's wierd, but it works. I tried a cure for vaginal yeast infection to help with my candida issues - taking a clove of fresh garlic, making a few fingernail indentations and placing it in the vagina at night while you sleep. Within a few minutes of doing this, my sinus cavities open up significantly. I know it's wierd, but I've mentioned this on the Candida Forum and a few people agreed with me that it works.