Although slight discomfort can always be expected in the post extraction healing phase, severe pain after 7 days is still a worrisome sign. Were sutures placed on the wound after extraction??? Have they been removed already??? Extreme pain most commonly occurs due to lack of meticulous maintenance by the patient leading to the dislodgement of the blood clot causing a condition called as Dry socket. But the treatment for this can only be instituted only after the proper diagnosis has been confirmed clinically. You can choose to consult another dentist for a second opinion. Alternatively you can post the clinical picture and the post extraction xrays on Practo for online consultation with a specialist. Regards.