There isn't sufficient information to reach a specific diagnosis, there is a possibility of cervical lymphadenitis. You can do salt water gargle with lukewarm water thrice a day so as to control any local infections. I would advise you to meet a ENT so that you can be examined and undergo necessary investigations such as CBC, etc to find the underlying cause and have it treated accordingly.
Next Steps
Follow the steps as advised
Health Tips
If condition persists or worsens visit the ER at the earliest