hello and welcome to HCM forum,
i would like to inform you that a lump which has suddenly appeared needs to be checked thoroughly by the dentist
, it may increase in increase over time, i therefore advise you to see a dentist.
Do not worry, the lump may be normally present, just to make sure nothing is wrong kindly visit your dentist.
The lump may be due to an infection and subside as the infection resolves,
Dentist may prescribe medication if required,
i hope i answered your query,
i wish you good health,