In other words, the migraine isn't the addition of pain, but the absense of a pain relief mechanism. I have no sources to back this up, other than personal observation.
I have suffered them myself, and they always came in a sequence: arm pain, neck pain, headache and aura. Finally, I'd release tension in my neck and it'd be gone.
My doctor confirmed injuries in cervical discs also seem to be causally linked to auras, but there might be other causes as well.
That's why you get a headache from caffeine withdrawal at least, because the blood flow to your brain increases and you then feel the pounding.
Like right now for me wtf
One feature of migraines is not just a headache. Some people can feel it coming, called the aura. I feel weird during and after the headache. I frequently get the migraine weird feeling without the headache, so-called silent migraine. Migraines and normal headaches feel different.