Hi. As per what you have mentioned and seeing your age, your wisdom tooth would have erupted but the gum covering it (called operculum) is still persistent. Hence, when u bite, it gets compressed between the upper and lower teeth, causing it to swell up and pain. Also, food debris might accumulate underneath it, causing it to swell n pain. Visit a dentist/periodontist. You are having a problem called Pericoronitis. Based on the X-ray and clinical examination, the dentist will decide to retain that tooth and just remove the gum covering it, so that it will not interfere and will remain clean or remove the tooth (considering that it’s the wisdom tooth)

Hi..it can be treated by scaling and laser gum treatment

swollen gums near last molar  may be because wisdom tooth is erupting  constant pressure  from opposing tooth while chewing  aggrivates swelling .  brushing also  difficult due to swelling need  good clinical  check up . with proper medicine and treatment  swelling will reduce.

Wisdom tooth must b eruptying .get it examined by a dentist n by den use salt in lukewarm water for gargles for temporary relief

It could be due to cheek bite near your wisdom tooth. It is not something to worry about but get it checked so if the wisdom tooth requires any treatment it can be done