But if you mean I've read more and struggled to try and understand more then, maybe I've only got a year or more head start on you?

As for my own onset, it is considered 'middling' meaning technically 'semi-acute'...which further means I was hospitalized five weeks after my toes started to go numb and at the point I could barely walk nor hold a glass of water unless working hard with two hands. As for the pain? At the time I finally got INTO the hospital after 14 hours in an ER wait room, plus another 8 hours in an exam room then getting to a hospital room, I was finally given what I assume were heavy duty narcotics. They did not do one durned thing for the pain I was experiencing, they only slurred my speech to the point no one really tried to listen to whatever I tried to say. Sudden from start to finish wasn't my whole experience tho? The day I was told to go to the ER by my GP was one day in which I felt as if: I'd been dropped into a vat of dry ice for a while; then taken out to thaw; then reinserted into a french fry vat the size of a human; then tossed into a snow bank...lastly left to fend for myself. Nerves were fried, muscles, semi so, and the rest was to be determined.
OK so five weeks? The last 36 hours before conceding I should go to the hospital and the time in the hospital were the absolute worst. But, like many who experience this all, I lived thru it. I got a close diagnosis by the ER physician, but not close enough. I got less care from the Neuro on call at the time. Changing neuros saved my life. It was probably GBS but not severe enough to cause respiratory s/e's, Untreated, it became CIDP. IF they'd been quick enough on the uptake and I'd gotten IVIG or Plasmapherisis at that time? I might be a 'past patient' with 'some residuals' now. This is real life tho....but, I am improving in small ways.
As for the migraines being connected? I don't think I've read of any direct connections between the two? PN an Migraines...But I DO know that my neuro-opthamologist DID check out this aspect far more thoroughly than I could ever document!
I guess what I'm trying to say is that, YOU KNOW what tests you've had. You can get copies of them and then map them out 'a 'la Liza Jane or other sources and then,,, take a look for 'patterns'. IF there are any, such as blood sugar or potassium [too much/little?] then you mite be onto some things. Same with Calciums, Magnesiums, Vite-D's, Vite-B's etc. You get the drift? What really helps YOU is if you can get copies of tests from way before you started having problems...That's your base-line or maybe indicator for possible problems left un-tended. [I know I found heaps of 'border issues' well after the facts?-DUH]
We ALL wrestle with the What-if's and IF-only's...but we simply did'nt KNOW! What is done, is so, what WE can do is try to look forward and get ourselves into the best positions to help heal and help ourselves.
You have to take control and be in control of how you are cared for! Only you can do that! If we can help, by virture of good/bad experiences, then learn and benefit.
Hugs till later! - j