This could be a dental concern. Visiting dentist in the USA would be the best thing to do, as soon as possible. They will take X-ray's, and immediately diagnose what is causing a long lasting pathology. It should be considered in priority.
Could be
1. Wisdom tooth infection or malpossition
2. Bone fracture
3. Cyst
4. Parotid gland swelling
Next Steps
It would be helpful to describe how this swelling started and any history of trauma etc?
Health Tips
Consider it a Priority.