Do you get visual disturbances with them? Are you sensitive to light and/or sound while you have them? Are they worse on one side than the other? Do you have throbbing or pulsating pain? Does it feel like you have a tight band around your head? Does movement make it worse? Do you have neck and/or sinus pain with them?
This article describes the different types of headaches, although post-concussive headaches don't always fit neatly into these categories.
http://health.usnews.com/health-cond...dache/symptoms