Hello, I can understand your concern. It would have been more helpful if you had described what dental treatment you have been through few days ago and was the treatment on the right only? If that is the case and if you have been through root canal treatment, it is possible that the body has reacted to the treatment regarding the disinfectants and filling materials. In such situation, you should go back to the dentist and get the root canal related complication treated. It is also possible that hematoma has formed in the area if you were given local anesthesia. If that is the case, then the hematoma will resolve on its own in a few days. Ice application and over the counter analgesics such as Ibuprofen can help til then. Alternatively, it could be a new infection and abscess formation related to the oral cavity. My advise to you is to visit your treating dentist again for follow up of the previous treatment and to diagnose if any new infection has set in. In case of infection, you might have to take a course of antibiotics. I hope this information helps you. Thank you for choosing HealthcareMagic. I wish you feel better soon. Best, Dr. Viraj Shah