From the symptoms you described (painful & swollen gums), it seems like you have a case of acute pericoronal tissue infection (meaning inflammation of the tissue around the crown of the wisdom tooth).
This is commonly observed when there is a food (bacteria) trap caused by the partially erupting wisdom tooth. If left unattended, the infection may spread and cause your lymph nodes or face to swell too.
Removal of the infected wisdom tooth is the most common treatment method and it will help to prevent any future infection. During the process of removal, your oral surgeon/dentist will also help to clean the area thoroughly. Antibiotics will also be given after the wisdom tooth surgery to control the infection.
If you are already experiencing pain and swelling, you are recommended to visit an oral surgeon/dentist for treatment as soon as possible to prevent the condition from worsening.
Dr Ho Kok Sen