Hello pingh
I am sorry your girlfriend is having to deal with this and you are having to deal with her suffering. It is a hard road to hoe to be there for those of us with anxiety - you are to be commended for your patience and support.
There are many manifestations of anxiety. For me it's an overall malaise and a crushing feeling in my chest and upper abdomen. For me, anxiety feels like when you get word that someone you love has been in an accident and you are rushing to the hospital - only the feeling is there 24 hours a day.
I don't know about calling an ambulance but I was taken by my sister to the ER twice - not because she or I thought I was having a heart attack - we knew it was anxiety - but I had to get some relief in some way.
It's scary I know. Someone else will post with more helpful info than I've been able to provide.
Krista