You can develop claustrophobia from the way you think about body symptoms, and the way you behave in response to the anxiety that the thoughts give you. So let's say your trigger is stomach pain. If you are really worried about this stomach pain, you might think that you have stomach cancer, or you might die from this, or you can't stand being uncertain about this. These unsettling thoughts then lead to anxiety, and the anxiety leads to overcompensating behaviors, such as over-checking, over-educating, multiple doctor visits, and obtaining multiple medical tests. Unfortunately, your behaviors maintain your intolerance of uncertainty, and this continues your negative, vicious cycle of claustrophobia.