Recurrent pain that is not due to an injury to the body is often mediated by a process called central sensitization, where the sensory regions in the brain become oversensitive. It is possible that central sensitization is involved in migraine pain in the areas of the face and head where the trigeminal nerve mediates sensation.
A 2020 articleTrusted Source suggests that central sensitization may contribute to the intensity of migraine episode pain.
One chemical that may be involved in migraine episode pain is calcitonin gene-related peptide (CGRP). The trigeminal nerve produces large amounts of CGRP in response to pain signals, which may lead to migraine episode pain.