Post-traumatic headache (PTH) is the most common symptom following mild traumatic brain injury (mTBI). Some PTHs resolve within the first few days of onset, even without any specific treatment. However, in a large proportion of individuals the PTHs do not resolve and they last for many months to years. These persistent PTHs cause substantial pain and disability. There are no approved treatments for PTH and treatments currently used for other headache disorders typically provide little benefit for those with persistent PTH. Optimally, individuals who are at high risk for PTH persistence would be identified and treated, with the intent of preventing headache persistence. Currently, methods to prevent PTH persistence have not been found since the mechanisms responsible for PTH persistence are largely unknown, predictors for PTH persistence have not been identified, and treatments for PTH have not been adequately studied. This research includes a clinical trial that will test a newly developed medication that targets a mechanism of persistent headache pain. This treatment, a calcitonin gene-related peptide (CGRP) receptor monoclonal antibody, has just recently shown to be very effective for treating migraine and has received FDA approval for treating migraine.