You have greenish or yellowish nasal discharge. You are also experiencing vision problems, such as blurred or double vision. Your sinus pain begins after underwater diving. These compartments, which regularly produce mucus, have very small openings that readily swell shut in response to irritants like cigarette smoke, colds or allergies. Once the tiny openings of the sinuses are obstructed, the mucus they produce can't drain out.
Fluids build up in the cavities, causing pressure and pain.
It's easy to see why problems develop so readily. Besides being tiny and prone to swelling shut, the openings that drain your maxillary sinuses are inconveniently located. The openings for the maxillary sinuses behind the cheekbones, for example, are located at the top of the sinus. Besides closing in response to exposure to smoke and viruses, these passages may close when allergens cause the tissue to swell or from air pressure changes, such as when an airplane descends. And infections can cause a benign nasal growth called a polyp that can make a sinus problem even worse.