MRI is tomorrow. Doc prescribed imitrex but it doesn't seem to help much. I had two headaches back-to-back yesterday. It's worrisome because I'm starting my dog training business and don't want to have to cancel on a client because of a headache. But, once I get them, I'm incapacitated for several hours.

Can the MRI definitively diagnose a cluster headache? I thought he was just ruling out other things.