This study will analyze the effectiveness of a medication called Frovatriptan, in the context of medication overuse headache (MOH). MOH is a headache that develops when pain-killers are taken frequently. The treatment is to stop the overuse of these pain-killers, but that can sometimes worsen the headache first before it gets better. We are testing Frovatriptan against placebo to see if it can help patients with this transition and avoid the worsening of the headache that can occur. We will also see if Frovatriptan can help in other ways, such as maintain patients free of medication overuse.