Finding his triggers and getting enough rest and drinking lots of water helps as well.

400 mg of magnesium per day. Has helped me so much.
Magnesium/calcium/vitamin d suppliment.
He is in his growth years and can be difficient in these. I also take omega 3, co-q10 and b complex.
Naproxen and anti nausea for the pain

I take low dose aspirin every other day. I also have complex migraines but since I started taking the aspirin almost 2 months ago, GONE. Good luck to him, I know how hard that is.

My son is 15 startes having migraines at 5 we just now got him on medication to prevent migraines but it makes you sleepy so he takes it at night. They said he was so young that if they put him on medicine he would be on narcotics by the time he 18. They startes getting worse lasting longer I demanded some help. I hooe it works

Be persistent to get him help. It may take a while to get a correct mix of diagnosis and treatment. Over the counter, Motrin extra strength, Aleve extra strength, drink lots of water stay hydrated