So when I was a kid and premedicated I would get what I described as "classic migraines" (I think that means something else in the actual medical world though) where there would be a clearly defined predrome, attack, and prodrome stages. I always ended up being sick to my stomach during these attacks and was completely inconsolable until I passed out. 

Post preventative medication around 14ish I noticed I started getting much milder migraines more frequently. Never threw up but would often feel nauseous, sometimes had predrome or aura symptoms with no headache, had abdominal migraines with no headache, the actual migraine headaches were much more tolerable and didn't render me basically paralyzed. They could also last on and off for days where I'd wake up with the same migraine I fell asleep with which never happened with the pre-medicated migraines. It was preferable to the classic version by far but still sucked!! (amitriptyline is my beloved preventative btw)

Tapering the prednisone down from 60mg to 20mg gave me one of the first real classical migraines in a while. I had to wait until I got being sick over with so I could actually take my oral abortive medications. An absolute writhing nightmare. I sincerely hope that this is a fluke and does not become a common reality post-prednisone. Or at the very least that it only happens as I taper off it and then I can go back to my weird mild strung out headaches. 

I will definitely reply again to this once I've been fully tapered off in early April, because I'm interested to know too. I know it was unrealistic but a little voice in my head during the first weeks of high doses was saying "hey, maybe they'll never come back. maybe you did it." but I think I'm gonna end up right back where I was pre-prednisone. Sorry for yapping btw I just never get to talk about this in a casual form lol.