3 neck glands swollen on my right side. no pain, but a lot of drainage and occasional stuffy nose. sinus infection or viral infection?

Could be either, or?: You are correct in presuming that typically swollen lymph nodes are due to an infection nearby. Bacterial infections may be more likely to cause this than viral, but both can do it. Laryngeal/throat infection more likely to cause than higher up sinuses. Watch these glands. If they don't resolve in 2-3 weeks, have your doctor examine you. Sometimes enlarged lymph nodes are tumor, not infection.