Ok here is something I have been thinking about. When she has a migraine, does it go away when the sun goes down?? When I was younger and I would get them, they would last all day until the sun went down. (I know this sounds weird, but its true)
With my migraines, no over the counter medicine will work, I suffered for many years. Then I moved to Florida and got a new MD. She put me on Imitrex. Its a life saver. Of course you wouldn't want to put your daughter on meds if she doesn't have to. But its truely a wonderful medication.
When I have migraines sometimes I have to throw up (which means I can not keep the pill form of the medication down) I throw up everthing, even the water I use to rinse out my mouth from brushing my teeth. But now I have the injection type (statdose) and within 15 minutes, the pain is gone!
I still have to lay down, but after an hour or 2 I'm GREAT!
Another thing to check into is the pollen counts, Keep your self as record of her migraines and the pollen count in your area, You might find a connection.
Keep us informed about your daughter. Hope you find some relief for her!