I get this too, but it's because my anxiety includes fear of heights. So it could be that.
It's difficult to say if your anxiety is causing the pain upon exertion or your fear of it, is causing it and the panic attack. If you're not being treated for your anxiety, this is where your focus needs to be right now. Normally when one has chest pain upon exertion, anything to do with the heart would be revealed in testing. Since tests have ruled out your heart, get help with the anxiety and go from there. Maybe once your anxiety is under control, your chest pain will go away. Anxiety can cause this, and many other problems, so please address this right away so that you can put it to rest and get on with life. I wish you all the best and take care.