Dear werewolfgirl, here is my list of things to do fix your sinuses.
1) What does your home smell like? Make sure your home smells clean and fresh like a nice hospital or museum. (no scented candles,etc.) You must make sure you have no moisture leaks in your home anywhere. Inspect outside for any allergans that may be coming in through your air intake.
2) Buy the best air filter you can and stick it in your bedroom. I spent $900 on mine, worth every penny, and wish I did it sooner. Your health is the most important thing and once your feeling better you will easily make back all that money spent.
3) clean all sheets, pillows, bedding regularly. Up to 90% of people have allergies to dust mites.
4) Get a cat scan to make sure your sinuses appear clear. You may have polyps or something that prevents the sinus from draining. (A clear cat scan does not mean you don't have an infection irrespective of what any doctor tells you)
5) Moisten the sinuses using sinus rinses and humidifiers (read online). It took me 7 months of sinus rinsing until I could really begin to clear out my infection.
6) Dietary Changes (you are already doing this). Cut out wheat, dairy very good idea.
7) Take a mucolytic agent to thin the mucous.
8) Once your sinuses begin draining and things are clearing up, you should be able to "sense" the infection. It does not mean pain or major pressure or anything, you will just know you have an infection. Try A round of good antibiotics (i.e. skip the penicillin, you need something stronger). Do not do this until you think you are on the road to recovery, otherwise you will make things worse.
9) Read online about alternative treatments for sinus infections and keep trying stuff.
If you are feeling sick, sinuses seem clogged, I believe you have an infection. The cat scan may be clear even with an infection and mucous may be clear as well but probably thick. Staph likes to sit up there and produce endotoxins (A, B, C and D) causing an inflammatory response which creates a cycle of clogged sinuses, bacteria growth, and more toxins. So you need to remove any allergans that cause inflammation, kill the bacteria, and rinse out the toxins that get trapped in the mucous. The staph toxins are what make you feel so tired, drained and exhausted.
Hope this helps and you start feeling better soon. It will be a rollercoaster, some days better some days worse. You will need to evaluate over months not days.