hello there and welcome,
It is caused due poor oral hygiene
,improper brushing and flossing that leads to accumulation of bacterial plaque
and calculus deep in the gum pockets and root surfaces of the teeth.
It presents with symptoms of redness
, bleeding gums
, swelling , pain ,recession and sensitivity.
It needs to be treated by thorough professional deep scaling of gums and root planing of the teeth to remove all the irritants ,this will help in resolving the symptoms followed by a course of antibiotic and analgesics.
exact diagnosis can be made only after clinical examination and evaluation by taking radiograph.
Accordingly if the prognosis of the tooth is poor and the tooth is mobile , you can go for extraction of the tooth.
i hope this helps,