Is that tiny pimple like bump is paining.
It is just a minor salivary gland
opening which might be getting blocked at its duct causing the swelling.
It bursts automatically as the pressure rises inside. It reappears as the glandular fluid again start depositing inside.
Please consult some Dentist/Oral Pathologist in nearby area to get a biopsy
done to rule out any other invasive activity.
Hope this helps.
Get well soon.
Dr. Himanshu Govil