Hey Levi,
I'm sorry I was rambling off lots of ideas in my previous post. I'm just not sure what is wrong with you but I definitely believe something is. I totally understand about the doctors putting everything down to Anxiety. Myself, I suffer from severe chest pain which radiates down my left arm, pretty much whenever it likes and I went to my doctor about this. My heart was beating very fast and after 10minutes of this my doctor said I was hyperventilating! I was completely calm. I think doctors are pretty useless. They NEED telling what to do most of the time, lol.
The doctors should of investigated WHY you couldn't run on the treadmill just as they should of investigated why the GTN spray made your chest pains worse. If I was a doctor I certianly would of and not left one stone un-turned. But Im not so I wont go there.
I cant really say if Angina..unstable angina, will show up on an ECK/EKG or Echo. It did with my father but not with my grandmother. So I cant say 100% just that in some people it does and in others it doesn't.
However, I do know that Angiograms are pretty good at finding out whats wrong with you. A small camera is inserted into your groin which looks closely at your heart and can find any abnormalities. This test worked for my grandmother and also, for my dad. So I would recommend you having this test done. If you have a cardiologist tell him/her that you want the Angiogram. If you dont have one currently, be referred to one via your doctor.
As far as I know DVT does occur in the legs and I beleive its more common in those who have varicose veins. I dont think thrombosis shows on an EKG or Echo. The tests which are usually carried out in diagnosising DVT are blood tests to check the clotting properties of the blood, and unltrasound scan and also a dye can be injected into your veins then you will have a X-ray which will show up any abnormalities or DVT.
DVT, if you have one, usually travel to the lung but in my experience they have travelled to the heart. My grandmother had no idea she had a DVT, she had this pain in her leg then she went to lie down. Less than 10minutes later she was having a major heart attack. We were told she had DVT in her leg, a blood clot had formed and travelled up to her heart, causing her heart attack.
I dont want to worry you. Just trying to explain.

But if you do think you might have a DVT then by all means, be examined for one.
What I said above are just ideas (in my previous post). I dont want to say you have something when its possible you have none of the things I have mentioned. Good Luck