First of all, I don't think its ridiculous. What you are talking about is what led me to my first therapy session. One day I was laying on the couch and my whole left side became numb.........Of course I figured it must be something neurological, as did my GP. I was sent of for an MRI of my brain as well as an EEG. They both showed there was nothing wrong with me physically.
I refused to believe that it may be the anxiety that is causing this, so I asked to be retested, again nothing wrong ? No word of a lie, I must of been tested for pretty much everything during my life, and thankfully I always get the same result, nothings wrong.
However, if you do feel you may have some medical issue, defiantly tell your GP
Personally, anxiety is very good at manifesting itself into physical symptoms to distract me from what is driving the anxiety. Even now reading back on what I've written I notice that I refer to Anxiety as "The anxiety" I can't take ownership of it. I think it's the label that bugs me, maybe you are feeling the same ?
The point is yes, anxiety can be a self for filling prophesy.