I have managed to keep my migraines at bay for a couple of years after I discovered that my poor neck posture appears to be the cause. I have completely flat feet and if I don't wear 'proper' orthotics I find I jut my neck out!. ..also using ipad/phone use etc. There is fluid that flows from the brain down the spinal cord which gets rid of waste products from the brain - my neck position seems to pinch this and eventually lead to a migraine!. I now can feel when things are building up for a migraine, and it is always when I've been using a laptop or ipad in bed etc (ie. Poor neck position). Hope this helps someone!
Here is an enhanced MRI showing brain fluid flow!
youtu.be/bC05R_tcyW4?si=vMG...
Really just sharing to try and help others, as it took me 40yrs to find a cause!