If you have ongoing problems with nasal mucus and sinus congestion, then it is possible that bacteria can become lodged in your sinuses and develop into a sinus infection.  Symptoms of a sinus infections include prolonged sinus pressure, congestion, pain, or a headache for more than seven days. If you develop a fever, you may have a sinus infection. If the mucus changes to a greenish or yellowish color instead of clear or develops an odor, then you may have bacteria growing in your sinus passages leading to a sinus infection.  When your sinuses get blocked with congestion, the mucus, and bacteria that is normally produced gets trapped. If the congestion and pressure are not relieved, the trapped bacteria can lead to a sinus infection. You may also get a viral sinus infection if the congestion and pressure were caused by a cold or the flu. Antibiotics are ineffective if the infection is due to a virus. If you have a cold or flu virus, treat with zinc, vitamin C, and/or pseudoephedrine. If your doctor determines that you have developed a bacterial sinus infection, antibiotics may be prescribed for you. Be sure you take them exactly as prescribed and for the full duration of the prescription.  Even if you start to feel better quickly, finish the prescription as prescribed. Not doing so may result in resistive strains of bacteria. It is also beneficial as the bacteria can still be lingering in your sinus passages. Be aware that some doctors may prescribe antibiotics before receiving test results that identify the actual cause of infection. You may ask for a culture to be taken to be sure the correct antibiotic is prescribed. If the symptoms persist even after you have finished the course of antibiotics, let your doctor know. You may need another course or a different antibiotic. Talk to your doctor about allergy testing or other preventive measures if this happens to you frequently. Some situations of excessive mucus production seem to go on and on, no matter what treatments you try.  If you have persistent...

TL;DR in Vietnamese:
Hãy tìm đến bác sĩ nếu bạn có dấu hiệu bị viêm nhiễm. Theo dõi sự thay đổi của nước mũi. Uống kháng sinh theo chỉ định của bác sĩ. Tìm kiếm sự trợ giúp về mặt y tế nếu tình trạng chảy nước mũi kéo dài. Hỏi ý kiến bác sĩ về các bất thường cấu trúc mũi.