welcome to HCM!
I have gone through your question and from my clinical experince I can say that sunlight triggers migraneous attack in your daughter, which is a sever one.
As she is just 9 years, I would not advice for any prophylactic medicine for long term, espically when attacks come only when she goes in sun, and not otherwise ( at least it is not mentioned in question that she otherwise also gets them). Had I been treating her, I would also advice that it will be wise if she can avoid strong sun light, at least prevention is better than cure!
Also, these attacks can become more intense if she continues to face the triggering factor.
I know you are concerned that she can't play like other kids, and there is lot of difficulty in taking her out in sun, but this is her body, we can't change it. If attack can be prevented with avoiding one thing, I think it is better than taking so many medicines.
Just like in allergies, one has to avoid the triggers and later the sensitivity sometimes reduce itself, similar is also seen with migraines.
Avoding tea, coffee, cold
drinks also help in some cases.
It is better to avoid attacks, even for long term prognosis, and not to go for continuos treatment.
Still if she develops an attack, I have found good response with naproxen
sodium and domperidone
combination given as soon as she gets an attack. This usually aborts the attack within ten to fifteen minutes, and there is no vomiting
Hope the reply is helpful.
Feel free to ask more questions
Dr. Manisha Gopal.