Sudden Onset Headaches

My 15 year old daughter sufferered complete kidney loss last year after a severe vasculitis episode. One month after beginning dialysis she had a large hemorrhagic stroke.  The headaches for several weeks after were awful but finally stopped.  It has been a year since the stroke and now there are recurrent headaches which are severe enough to require IV morphine for relief. I am afraid they are going to cancel her kidney transplant because these are "unexplained" although "not suprising".  The neurologist states they seem to be migraines but no one has felt another CT scan is necessary.  They tried her on Elavil last week and the side effects of involuntary muscle movements were awful.  What tests should I insist on?