Would an ulcer cause migraines?

ul·cer
noun
an open sore on an external or internal surface of the body, caused by a break in the skin or mucous membrane that fails to heal.
synonyms: sore, ulceration, abscess, boil, carbuncle, blister, gumboil, cyst;
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An ulcer is a mechanical symptom. It does not cause anything, although whatever causes the ulcer might cause other symptoms.

Nobody knows what causes migraine.