Hi Cassie,
I too thought I had brain tumors. I even asked my doctor for an MRI she said I didn't need one and that I dont have a brain tumor. I had many of the symptoms you have, dizziness, eye disturbances - what you may have are floaters, they looks like zig zags that float across your eye and when you move your eye they move, they are harmless but irritating. I was spaced out, shaky and was tired all the time. She put me on Paxil Cr and Ativan, (same as you SSRI and and a benzo) I have been on Paxil Cr for a week now, initailly I felt worse, still don't feel it working at all, I was nauseaus and shaky but they say that is normal. Some people get a bit worse before they get better and it takes 2-3 weeks for the SSRI's to work properly so I guess I wont know if this will do the trick for another week.
It is really scary, Anxiety can mimick alot of things, the WORSE thing you can do is look up symptoms on the net...that got me into major panic mode. The more you think about a brain tumor the more anxious you will get and the worse your symptoms will be. I feel your pain but just hang in there...try the meds. I had the worst fear ever of them but I finally got sick and tired of all this, I'm willing to do anything...and I'm sure you are at that point to.