Hi.. Can understand your concern... As per your complain it seems that you have a pus draining sinus and it is caused due to infection in the area leading to pus formation and many a times an opening is created over the bump from where pus is drained off.. You should re-check that whether it is exactly over the gums from where wisdom tooth was extracted or it is near that area as any deep seated infection in the tooth adjacent to the wisdom tooth area can also lead to sinus formation.. If it is exactly at the area from where wisdom tooth was extracted it can be due to infection in the extraction socket which can be either due to any left out piece of tooth root or due to any foreign body which got entrapped in the socket and now leading to infection and pus formation. If it is due to adjacent tooth then the treatment of the same has to be done.. I would suggest you to consult a dentist and get evaluated for the cause of sinus formation by getting clinical evaluation and IOPAR (x ray) done to rule out the cause of it.. In case of any root pieces or foreign body in the wisdom tooth healing socket it will be needed to get removed followed by antibiotics and painkillers. In case of infection in adjacent tooth treatment either with root canal treatment or extraction can be done. Hope your query is solved.. If you find the answer helpful please write a positive review and click on find this answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora.