Hello and welcome to hcm forum,
The lump may be due to impacted wisdom tooth
which is infected.
yOU can go for a second opinion
Drink plenty of water and fluids.
The tooth has to be either extracted or flap overlying tooth has to be removed to enhance tooth eruption
Maintain good oral hygiene
Take complete course of antibiotics and analgesics.
Pus has to be drained if present within the lump.