What will cause chronic migraines?

Blood flow changes? The actual cause of migraine headaches is not known. The vascular theory says that changes in the size of blood vessels leading to the brain causes changes in blood flow, with increased flow causing pain. The neurovascular theory says changes in brain signals and brain activity cause blood vessels to change sizes, resulting in pain from increases in blood flow. Additional theories also exist.
Chronic daliy HA's. Migraine is a hereditary condition where headaches can be triggered by a variety of issues, such as foods, red wines, stress, weather changes, etc. Headaches can transform to virtually constant events if pain medication is used too frequently, and the main contributor to these is actually tylenol, (acetaminophen) but other analgesics can cause it too. Tough to disrupt but can be done.