I can only give you advise on what to expect with an MRI. They slide you in a tube and if you are not too thrilled with small spaces you can request an open MRI machine. However if no open MRI is available you could be somewhat sedated as you will need to be kept still, especially your head.
I've had several Brain MRI's with and without contrast. In this case they take take layers of pics (I believe called slices) and then I am injected (arm) with a dye and slid back into the machine and take more pics...this procedure takes approx 45 minutes.
Go see your neurologist and get an MRI so that you can begin treatment so that you may soon have an answer and on the path to recovery.
Take care,
~Zig