Benito, an Aortic Aneurysm can be tested for. I think one test they do is an ultrasound. Would your doctor arrange this?
I think (I am not a medical person) you need an internist who is committed to finding out the cause of this. I am not thinking it is something horrible. I imagine even a pinched nerve in the right place can cause this, but no need to suffer about something that can be fixed once it is found.