Lump arised at the site of wisdom tooth may be due to-Abscess
developed due to gingivitis
or deep caries.
I would advice you to get a deep scaling done.
A detailed clinical as well as x-ray evaluation will give the diagnosis.
Pus has to be drained and curetted.
Take complete course of antibiotics-analgesics.
Rinse your mouth after every meals.
Gargle frequently using warm saline or chlorhexidine
Hope this helps.