Cyproheptadine
"My child was diagnosed with cluster migraines when he was only 3.5 yrs old.  This is very unusual.  We refused to put him on anti-seizure medicines, which the Dr. said has the side effect of helping migraines.  Instead we opted for Cyproheptadine and it has worked wonders and improved his quality of life by 100 fold.  Yes, have to watch that weight gain but otherwise it has been a miracle."