What Causes Vision Disturbance Followed By Slight Migraine?

Hi,I am male, white, 60 yrs old with a history of migraines and depression. Today (about 2 hrs ago) I experienced a coloured pinwheel in the right side of my vision accompanied by vision loss close to the centre of my vision. Nothing unusual has happened to me except a lower-level migraine that has been hanging on for over a week. Pain at the base of the skull instead of the usual behind-the-eye type I usually get. Also have had a feeling of low blood pressure ( funny hearing ) for a week.
Thank you