Thanks for asking the query,
Your clinical history suggest that due to infection in the tooth there is formation of abscess
that had to the surrounding tissue leading to formation lump which is bulging out externally.
This type of an abscess cavity need to be drained .
Take complete course of antibiotic and analgesic
Take the x-ray of the involved tooth , most probably you have to go for root canal treatment of the tooth or apicectomy or if the condition of the tooth is poor it can extracted.
Take saline water gargles 3-4 times a day , use antiseptic mouthwash solution like chlorhexidine
twice daily to prevent infection and promote healing .
Hope this helps out .