I can relate to feeling that there is something catastrophically wrong with me and it causes me to have such anxiety that my chest gets tight and hurts. I know sometimes it's hard to hear the dr. tell you that nothing is wrong when you've convinced yourself something is. There is a great thread pinned on top of the forum that goes over physical symptoms that we can get from anxiety- you'd be surprised at all the ways anxiety manifests itself physically. When I was having chest pain last night (from anxiety about a heart issue- go figure), I read through that list and it really helped me work through those feelings- and surprise- the pain went away.
The pinned thread is called "This list is a life saver"