Hello, I'd like to help you with your question.
Anxiety is often manifested through physical symptoms. And many people who have anxiety initially feel they are suffering from a physical illness. Many seek out the ER because they feel they are having a heart attack or they have a brain tumor. So connecting anxiety to a physical illness is extremely common.
Feeling as if you are in a haze and not being able to focus is also a symptom of anxiety that is experienced by a good portion of those with anxiety disorder. You don't suddenly pick a belief of being physically ill so much as something triggers anxiety suddenly in your mind. The build up to it however could have taken a while. A childhood trauma that was unresolved or a long period of intense stress
. PTSD can also cause panic attacks. Whatever the cause, anxiety and panic can seem like it suddenly strikes and the first thought is that something is wrong with you physically.
While you might not be able to go back to a time when you were unaware of panic and anxiety, you can learn to deal with it so it does not dominate your life anymore. The fact that your girlfriend's comment having such an effect on you is proof that with some thought changing and understanding of anxiety and how it works, you can feel normal again.
You mentioned that you already see a therapist, which is good. Therapy is the best treatment. Also, learning more on your own can help you find ways to work on reducing or eliminating the anxiety and the belief connected to it. Here are some resources that can help you:
On line links:
The Anxiety and Phobia Workbook by Edmund J. Bourne
When Panic Attacks: The New, Drug-Free Anxiety Therapy That Can Change Your Life by David D. Burns
The Cognitive Behavioral Workbook for Anxiety: A Step-by-Step Program by William J. Knaus EdD and Jon Carlson PsyD EdD
Coping with Anxiety: 10 Simple Ways to Relieve Anxiety, Fear & Worry by Edmund J. Bourne and Lorna Garano
Take your time to find the resources that work for you. Some will and some won't. But as long as you keep moving forward with seeking answers, you will recover.
I hope this has helped you,