According to your age and description this is a probable case of pericoronitis related to impacted third molar or wisdom tooth. For confirmatory diagnosis clinical evaluation needed. After clinical evaluation and xray taken further procedure will be described.
Generally wisdom should get extracted.
Next Steps
visit nearby dental clinic asap
Health Tips
1)take pain killer (eg: zerodol-P) for pain relief.
2)warm salt water mouth gargle 3-4 times daily