my 15 year old daughter has been experiencing severe headaches for the last three weeks. No prior migraine history. No relief thus far from medications for migraines. She has episodes of vision loss - seeing only black. and dizziness. MRI appears normal; cat scan did show cerebellar tonsils extended but no malformation seen on MRI. The neurologist doesn't seem to think it could be the birth defect (Chari something) her headaches are isolated to the back of her head at the base of her neck only. She's not light/sound sensitive. Her blood pressure and heart rate has been low. We were told she's dehydrated but even after being hospitalized and on Iv fluids - she still keeps the headaches. We have to wait 2 weeks for a 2nd opinion from Children’s Hospital Neurology.