sydpop

My 16 yr old daughter has been going through episodes of dizziness to the point of almost passing out. She loses her vision and hearing. Lights In school seem to make it worse. She is wiped out afterwards. This has been going on for 4 years now. We have seen a CHOP cardiologist ( all testing normal) a neurologist ( who thinks she is having migraines but without the actual headache) and a hematologist ( all blood work normal) My daughter does tend to have low blood pressure at times and was advised to keep her salt levels and electrolytes up. Someone mentioned to me that she may have POTS, but I am not sure... Any advice??