Thyroid? Or something else? Constant internal shakiness

Going on 2months now everyday non stop. Sometimes mild and im able to ignore it but over the hours of day it becomes more severe and causing my heart rate to go up and my blood pressure to go very high (170/99) its episodic. Ive been to hospital for it 3 times for it and received no treatment as my vitals slowly return to normal. Xanex helps me feel calm but does not help the shakiness just helps me not get upset about it. Am only 28 years old and hypothyroid. I have never had symptoms like this in my entire life just started out of nowhere. Iam in good sTate of mind and aware of what's happening when the episodes happen. So far my doctors are clueless.