Firstly I'm sorry to hear your girlfriend is having these problems, nice that she has a partner to care for her!
I'm no doctor but looking at her symptoms reminds me a lot of me when I'm having one of my anxiety episodes. I suffer with anxiety on and off and when its really bad I have all the symptoms you mention. I get dizzy, lightheaded like I'm going to faint, constant headaches, feeling very emotional, weepy and nervous for no real reason. I also experience a 'heavy body' sensation often in my arms where I feel I can't coordinate them probably almost like they don't belong to me! very odd. I also at those times have panic symptoms in social situations which is very unlike me usually.
My anxiety symptoms however disappeared when I began to take propanolol for migraine prevention.
as I said I'm no doctor or expert just thought I'd let you know as its the first thing that sprung to mind when I read your post :)