after tooth extraction you need to follow the instructions as your
dentist says ,,no spitting for 24hrs, keep the cotton in place for about 20 min,no hot and hard diet,only
soft diet,, the main intention is to preserve the blood clot formed in empty space so that it will develop a bone in sequence and prevents food collection in extracted site,,in some cases the blood clot will not form or its removed by means of washing your mouth forcefully and some times unknown reasons, this leads to food collection in the wound and infection to open wound and bone causes pain,this is the most common causes in your case,, and treatment part your dentist is the best to treat the condition,,and as a home remedy ,,you can follow these,,use antiseptic mouth wash ,you can use luke warm water with salt,,gargle mouth after each meal,,see to that no food is entering in to the wound,,local
anesthetic gel will help you for time being,,take the medicine according to dentist advise ,,,