stand on your head...I don't know how, but it relieves the pressure. My Granny told me this when I was 6, and I've used it ever since...it really does work. For every minutes you stand on your head, you have about 1 hour of relief from sinus pressure.
(if you are wearing a skirt or dress at work, you may want to wait until you get home to try this)
_________________________
Providing alternative truths since the invention of time