I Am Currently Seeing A Cardiologist And Have A Heart

I am currently seeing a cardiologist and have a heart monitor on. I have had fainting and passing out spells, with low blood pressure, some dizziness and fatigue, along with all of this anxiety at night and just trying to get some sleep. One Dr. prescribed Xanax and sent me home. Cardiologist put monitor on me, I've had numerous tests, EKG, chest xray, MRI, CT, etc. What should I do next?