Hi Megan. I am sorry you're going through this. I hope you can get this resolved. I will tell you that I had episodes of very high BP a few years ago which were caused by anxiety and it became a cycle. Anxiety led to very high BP which made me scared and panicky which led to higher BP. I was already on BP medication but it didn't do anything. I was in the ER twice. The second time I was there they prescribed clonidine to take when I take my BP at home and it gets critically high. After lab tests which ruled out heart attacks, the doctors said it was anxiety causing this. Getting a handle on the anxiety is not easy and takes time. The important step is to rule out other causes. So, it's important to work with your doctor on this.
By the way, walking is great for blood pressure as well as the mind. I wish you well and hope you post back with updates!