Hi.. Can understand your concern.. As per your complain it can be dye to allergic reaction to any medicine causing inflammation and lump formation.. A white lump on the gum after wisdom tooth extraction can be due to injury caused by any extraction instrument to the gum in the region leading to inflammation in that region and formation of lump and white colour can be due to inflammatory exudate filled in it.. It can also be due to infection in the gum due to injury leading to stuffing of bacteria or some foreign body into the gums leading to pus formation and lump.. It can also be due to infected tooth associated with the gums which got activated leading to dental abscess formation and lump formation.. I would suggest you to consult a dentist and get clinical evaluation done and in case if it is due to Allergic reaction antihistamines like allegra or benadryl can be relieving.. In case of injury or infection in gums scaling followed by antibiotics and painkillers can relieve.. In case of infected tooth treatment of tooth by either root canal treatment or extraction can help.. Hope this information helps.. If you find the answer helpful please write a positive review and click on find this answer helpful.. Thanks and regards.. Dr.Honey Nandwani Arora.