Serious unidentified disease. Please help.?

I would have them check for mitochondrial diseases. There is over 300 of them. My son has had 9 years of seizures (never controlled) and just this month January was diagnosed with POTS (his body can no longer regulated blood pressure and heart rate. His heart rate ranges from 40-182. Blood pressure is real low. He is now on 2 blood pressure medicines that is helping prevent his fainting episodes. His new doctor a POTS specialist believes he has a mitochondrial disease that started the seizures and POTS. Sounds like you have lots going on which might describe a mito disease? If they can find the mito disorder you might be missing an enzyme that then can be supplemented and be able to get better.