Thanks for sharing Pic!
Appears to be infection around partially erupted wisdom tooth.
Please visit an Oral& Maxillofacial surgeon ,the tooth will need to be surgically removed after radiographic examination ,
Also ,you will benefit from cleaning as lot of plaque and calculus is there,which improves the overall oral health.
Next Steps
Consult an Oral &Maxillofacial Surgeon
Health Tips
Warm saline gargle will ease pain in the interim and flush clean the area