Welcome to healthcaremagic.
Large lump may be arised due to abscess
formed either due to deep caries or due to periodontal infection
A detailed clinical as well as x-ray evaluation is necessary to diagnose the problem associated.
I would suggest you to take augmentin
tab.along with analgesics.
Pus within the lump has to be drained if possible.
Meanwhile,maintain oral hygiene
If symptoms persists,biopsy of the lump will help to rule out the nature of tumor.
Hope this helps.