Well I have taken to watering my booze - and I only drink cider - 3.5% ABV at that. AND limit to 2 X 500ml cans or 4 if the day is a long one.
If your doc doesn't recommend a diet diary then do it anyway. It may be job/pillow/driving tension, it may be anorak and boring but compared to the migraines?
cause and effect and all that.
see the doc though.