You don't have to consciously be thinking of anything to have an anxiety attack. Sometimes something going on in your body can trigger it - like pain or other health issues. I had trouble with them when I had an undiagnosed inner ear problem. When I was finally diagnosed, my ENT told me that it was very common, and he would probably have them too if he had vertigo.
Sometimes, anxiety is the first symptom I'm aware of when I'm having an asthma attack. I'll start to feel really anxious (with some of the symptoms you mentioned) before I actually have "true" asthma symptoms.
I, personally, don't have them with pain, but I can see how pain would trigger anxiety in your brain before your thoughts even catch up.
The trick is learning to manage the anxiety once you do become aware of it. For me, just knowing that it was triggered by a reaction to a physical condition helped. Also, there are tons of good books/cd's out there to help with the emotional side of it. I like the anti-anxiety program by Lucinda Bassett and books based on the theories of Albert Ellis.
Post Edited (AustenFan) : 3/3/2014 6:05:01 AM (GMT-7)