See the dentist. Go back to the dentist and have it checked for too heavy a bite, and the health of the nerve, and the fit on the tooth.
Have dentist check. If your crown is new, have your dentist check the bite. If you've had crown for some time, have your dentist take an x-ray to see if there is an abscess or a cracked root. If there is an abscess, root canal treatment might be needed to allow you to save the tooth. If the root is cracked, the tooth may need removal.