Blocked Saliva Duct. A blocked saliva duct is caused by a mucus plug or a stone. Either occurs slowly, over time, and may lead to sudden blocking or plugging of the saliva duct. This will cause sudden swelling of the salivary gland. The two largest salivary glands are located in front of each ear, the parotid salivary gland. Drink plenty of fluids, massage the affected salivary gland, and suck on sour candy.
Blockage. Stones, scar and infections.