Sounds like you have confirmed POTS/autonomic dysfunction. All depending on the actual numbers (heart rate, BP, etc) during the testing, a betablocker is certainly appropriate and will likely help you feel better.

It is somewhat normal for increased anxiety whenever you are diagnosed with ANY condition that confirms an abnormal function...whether it be autonomic problems, PN, crdiac problems, cancer, etc...anything can bring about increased anxiety. Once you start treatment (and keep in mind it can take a while to fine tune dosing, etc) and start to feel better, your anxiety will likely settle down on its own.

A cardiologist or neurologist can manage autonomic problems. I have had both specialties do so. It all depends on the doctors comfort zone with handling somewhat outside the box type problems...as autonomic dysfunction isn't studied at length by all neurologist...same for cardiologist. You just have to ask your doctors if they are well versed in this area and comfortable in managing it for you.

Glad to hear you are getting some answers and well on your way to feeling better.