Welcome to HealingWell. Many people with migraines have tons of tests done that show no physical reason for the pain, doctors at headache clinics should know that. If you don't mind me asking, what headache clinic were you taking your son to? What type of pain does your son have (i.e. stabbing, throbbing, dull, etc...) and where is it located at? Has he had any allergy tests done?
I never wished pain on anyone until I started getting migraines and had to deal with so many doctors that didn't understand or care. Now I almost wish that every doctor had at least one migraine so they could be more compassionate and understanding when they get a migraine patient.
Best wishes to you and your son,