((((((Odrade))))))
Sorry you have to suffer from this. I too have suffered from migraines for most of my life-as have many in my family. And, like you, I don't usually know "if" it's going to turn into a migraine until it's too far gone.
One thing I usually try right away is a very strong cup of coffee. Many times a caffeine will do the trick if it's not a migraine coming on. If so, the relief is usually pretty quick.
I've tried weed too and the only way it works is in that "if" stage. It has helped to keep a migraine at bay unless it's one of the determined ones. It also helps to alleviate a bit of the nausea that accompanies most of mine.
I've made so many trips to the ER that now I have an aversion to them that is pretty strong. Because there are still so many unanswered questions about migraines, the medical profession treats them (and the sufferer) in all sorts of ways. In fact, I had never heard of Ativan or Thorazine being used. I guess they may use the Ativan for a sedative affect but Thorazine? My understanding is that it's a neuroleptic- an anti-psychotic drug. But, I guess if it brought you relief- what the heck !! My doctor prescribed heavy narcotics and compazine suppostitories for me so I don't have to make that ER trip and I usually have to find a very dark, quiet space and wait it out.
If you can catch the migraine in enough time that it doesn't become full-blown, THC may help you. After that it may not do much and could have you concentrating more on the pain you are experiencing.
My 145 cents. Good luck with it and (((((((((((hugs)))))))))))) for all those who suffer from these extremely painful headaches.
XW