Hi!
We call this an abscess in our medical terms & there can be many reasons for the same.
It would be wise not to guess the problem any further & get an expert opinion by a nearby dentist.
Next Steps
1. Cold compress on the right side(affected side).
2. Warm saline water rinses.
Health Tips
1. Start using mouthwash before sleeping as it is the main time of bacterial accumulation.
Mouthwash : Betadine(Just add 10 ml using the measuring cap that comes with the bottle itself & mix water & rinse)
2. Get an OPG done (It's an X-ray covering all your teeth in one frame) & then contact me for consultation I will guide you further about the situation & solution surely.