Hello, due to the residual infection present and also due to the reaction of the body sometimes causes pain. pain, redness, swelling are some of the signs that shows body is trying to protect. so need not worry it will go away soon. if it persists even after 2-3 days do concult a doctor as it can be a case of dry socket, where blood clots fail to form.

If pain is present within 2 to 5 days of extraction then you might have socket infection