Thanks for writing to us.
Lump on gum indicates inflammation of tooth which has spread periapically.
The pus has to be drained and curetted.
Get a thorough scaling done.
If deep caries associated,root canal treatment
has to be done.Amoxycillin
along with ANalgesics has to be administered.
Meanwhile,maintain oral hygiene
mouthrinses to gargle.
Hope this helps.