I started using a mini portable CO2 monitor and I quickly realized whenever levels rose to 900-1000ppm (parts per million), that my migraine pain would be greatly increased. I was able to predict high CO2 levels just based on when my pain was worsening. It seemed too simple and too unbelievable to be true, but simply opening windows when the CO2 levels were over 900ppm, reduced or nearly eliminated my migraines. Cars and airplanes, anyplace w/o open ventilation causes CO2 levels to dramatically rise. I had no idea just how high these levels are indoors, I believe it is an epidemic and by avoiding car exhaust and other air pollutants, we are inadvertently poisoning ourselves with high CO2 levels. I have had severe, debilitating chronic, constant migraine since 1998, its been a constant migraine of over 25 years and for the 1st time, I have some control over my pain. I never go anywhere w/o my CO2 monitor, I bought a couple, but the ARanet4 is small, and updates every 5 min, it is much better than the fancy monitors, having it with you all the time is the key to knowing when levels are high and that you need to get fresh outdoor air asap. It has changed my life. It has also improved my life beyond migraine pain, the high CO2 levels cause additional problems like fatigue, its worth doing a bit of research and ordering a monitor and seeing if your migraines are related to the CO2 levels. IT's possible that your migraines are triggered by CO2 levels that are higher or lower than my trigger CO2 number. There is research showing the connection between CO2 and migraines: https://pubmed.ncbi.nlm.nih.gov/8231977/
There is a lot of research available online, the pain caused by high CO2 is also related to cluster headaches, and possible other forms of head pain beyond migraine. I wish this info was more widely discussed and available, for it is the simplest and easiest pain solution I could ave imagined.
Link to Amazon, where you can buy a great CO2 monitor, though you can buy them from other vendors (I've bought others, but this is by far the most portable and reliable--I don't have any financial interest in the product): https://www.amazon.com/gp/product/B07YY7BH2W/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1