Take your son to a neurologist and don't waste time with a primary care physician.

I suffered from severe migraines as a child and into my 20's with symptoms of severe pain, loss of speech, impaired vision, and nausea. Primary care physicians eventually diagnosed me with migraines but did little for me despite their best efforts with a number of unsuccessful medications. I went to a neurologist in my mid-twenties and he resolved my problems with inexpensive medications.