Brief Answer:
Possibly a salivary gland stone.

Detailed Answer:
Hello, I'm Dr. Branch, thanks for using Ask a Doctor. The location that you describe your swelling sounds like it could be in the area of the parotid gland, which is one of the glands that produces saliva. Sometimes stones can form in the ducts leading out from the gland, usually causing swelling and pain, but can occasionally cause just swelling without pain. The swelling and pain can sometimes get worse with eating or in anticipation of eating, but sometimes the swelling is persistent at all times. A doctor can often diagnose a salivary gland stone based on physical exam, though occasionally further imaging will need to be done to confirm the diagnosis if there is any question.

There are other causes of salivary gland swelling, such as viral infections, bacterial infections, autoimmune diseases, and rarely salivary gland tumors, but your doctor should be able to distinguish between these based off of your history, other symptoms, and physical exam.

Management is usually conservative, including staying well hydrated, massaging the gland, and milking the duct from the gland to the mouth in order to help the stone pass. Medications that decrease production of saliva, such as Benadryl, should be avoided. If pain or fever develop, there may be a infection developing, for which you would need antibiotics.

I do recommend that you see your doctor about this to confirm the right diagnosis and to make sure that you are on the right treatment.

I hope that helps, please let me know if you have any other questions about that and I would be glad to discuss it with you further.

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