What are some natural options for a completey healthy patient with intertmittent cranial vascular headaches?

You mentioned that the patient is aware that certain stimuli cause the headaches. Keeping a detailed food journal for a month would be a good place to start, since additives such as MSG can trigger headaches like these; then the patient can try to avoid those foods. I would also look into bodywork such as chiropractic, osteopathy or craniosacral therapy to improve overall blood flow and correct any subluxations in the cervical area. Do they have a history of head or neck injury (TBI, concussion, whiplash, MVA, etc.)? Finally, did you already check reverse T3 against free T3 or do a cortisol saliva panel? If caffeine mitigates the headaches, that makes me wonder what is happening with the patient's adrenal glands. If adrenal fatigue is present, that could make the person more susceptible to whatever the triggers are.

One thing you might try is to have the patient learn to relax, and then imagine warming their hands in front of a fire. If you have access, a temperature sensor taped to the tip of the finger and connected to audio or visual feedback can enable a biofeedback of finger temperature. This basically reflects learning how to achieve peripheral vasodilation, which has some beneficial effect in conditions such as migraine relief.