Time to try clarithromycin , AKA (biaxin), and intraconazole
(sporanox), prilosec and peptobismol tablets.

Go to pubmed.gov and type in "biofilm sinusitis" and read what comes
up.
Do some further research on biofilms because you are not dealing with
one type of microbe, you are dealing with a microbial community.  You
get chronic sinusitis by after having the flu, when cilia and goblet
cells are killed by the virus. Bacteria move into the damaged area
while you defenses are down. Who moves in is whoever happens to be on
your tonsils and adenoid area, plus whatever bacteria happen to be
riding on the dust you breath in. Bacteria cling to surfaces, they
cling to dust. On the average air contains about 2000 bacteria per
cubic centimeter. In dusty conditions that can go up to a 1,000,000.
The medical community has characterized 640 or so human pathogens but
there are billions of types of bacteria, most of which will not grow
in the type of monocultures used for bacterial characterization in the
last century. Bacteria have a single cell wall and carry their DNA in
rings called plasmids throughout their cytoplasm. Bacteria generate
little prickles called sexual pilia and swap plasmids whenever they
are under stress in a process called bacterial conjugation, so the
bacteria that you have can be somewhat different from the similar
looking bacteria from the next town over. Usually bacteria are
classified into species by their shape, their gram stain (gram
positive or negative), which nutrients they metabolize, and the toxins
that they carry.
Bacteria of the Drugs may be standard, but the bacteria are not.
http://en.wikipedia.org/wiki/Bacterial_conjugation
One can find Staph, fungi, e-coli, actinomycetes and many others
living together in the biofilm and each one is resistant to the
antibiotics that inhibits or kills the other.
Search on   "Calgary Biofilm Device" to get some idea.

Bacteria that can be easily killed by amoxicillian in the free
floating state become effectively immune when growing in a biofilm. I
a biofilm about 15% of the microbiotia, including fungi are dormant.
They do not grow and they do not die in the presence of the antibiotic
or antifungal.  Only a few antibiotics are effective once they have
formed Voltron.
http://www.ncbi.nlm.nih.gov/pubmed/14734160

Despite their wild variability, most of the bugs that bother us live
in biofilms and share an attachment strategy. They make beta amyloid
to hold themselves together and to the host cell surfaces.  Staph uses
the fribronectin protein in plasma from wounds that it creates to
produce a clear springy insoluible mucus that serves the same
purpose.
Macrolide antibiotics, such as Biaxin, not only inhibit the
reproduction of the bacteria, they interfere with the production of
the extracellular goo that they produce to call home.
It not only takes just the right combination of antibiotics to kill a
bacterial biofilm, because of the presistor cells, the length of the
course of antibiotics that is necessary to get rid of the infection is
usually greater than the length of the course of antibiotics that the
doctor is willing to prescribe.
There are however some agents that can be used to help to peal the
film off a bit.
Look at the older post on the board and you will find reference to
Michaels tea wash, pecan tannins, splenda, and the use of Canada
balsam hair conditioner (which is gentle to the nose but contains
steryl alcohol, steralkonium cloride, glycerin, balsam canada, EDTA
and citric acid, all things which help depolymerize the god-awful
goo).
At this point you are in for some pain whenever you wash your nose
out, so take some Advil in advance, unless you are allergic to asprin,
because the inside of your nose is going to be raw under the blanket
of bugs that are chowing down on it. When they come off the area will
probably bleed a bit. Also the toxins in the post nasal drip can give
you severe heartburn, which will temporarily be much worse when you
try to get rid of them.

By the way. The bugs have their enemies too. Lysic phages.
http://www.phagetherapycenter.com/pii/PatientServlet?command=static_home

That's all they said???  Didn't the radiologist at least report on the
condition of your sinuses, whether the linings are swollen, the status
of your septum, etc.?

Get a copy of the radiologist's report and post it here.  Maybe we can
suggest some more things.