Your wisdom tooth is partially covered by the portion of your gum. So that portion has formed a small pocket in which the food and bacteria are having a good party therefore producing pus. Though you are not experiencing pain now, you should get it checked from a dentist and get the needful treatment done. Since, Prevention is better than cure, don’t wait for pain to develop.
Also till you visit your dentist, start warm water gargles with salt in it.
Next Steps
Visit your dentist and get checked.
Health Tips
Do warm water gargles with salt in it and DO NOT apply any kind of pain reliever ointment or gel on it.