I have had migraines since I was a small child myself, and I will never forget the hours laying by myself in my darkened bedroom.  I don't think my parents understood what was going on or how to help me and were too overwhelmed with my mom's cancer (she eventually died from it when I was 7) and then my father's having to raise 7 children on his own.  Please, please never neglect to spend time with your little girl when she has a migraine.  Cuddling, I have read, actually releases seritonin that can help lessen the pain.  Perhaps you can both be helped by some snuggling.  If she is too young to take medications like imitrex, I have had some success with Flexall (a muscle rub containing menthol)  I like this better than Head On because I can rub it where it hurts-often in my hair, without leaving my hair needing immediate washing.  I carefully rub it on my temples and eyebrows also.

Only a pediatrican could tell you what medicines to give her. I'm 63 now and have had migsaines for over 30 years. They are now controlled with imitrex. In my early years with them I rejected all meds because nothing worked. Although I sometimes used tylenol which didn't take it away but sometimes made me sleep a little and made the pain more bearable. I used icepacks too  and their are children's icepacks which she could hold on the spot which might make her feel like she has some control. Maybe an accupressure technique that she could learn or lying in a dark room with you listening to some soothing lullabies. I pray you find her some help, I hate to think of her suffering like that at her age.