I see on your post that you are taking plavix and nexium. Please check with your cardiolgist concerning these two meds taken together. According to the FDA the nexium inhibits the plavix from working properly. I also have a stent and was taking the nexium with plavix. My cardio took me off the nexium and put me on pepcid. Google plavix and nexium to get more info on this subject or go to the FDA website.
That is not a very good diagnosis to have a doctor say what is not the cause. Did the doctor prescribe a nitrate for chest pains? If it is not the heart, did (s)he refer you to a pulmonary specialist? Is the chest pain the same as your original pain?
There are many causes for chest pains, and a good doctor wouldn't tell you what isn't the cause and then dismiss any responsibility for further examination or referal.
Sometimes the chest pains can be due to medication. When I came off beta blockers I found a lot of chest pain stopped. Are your chest pains associated with exertion or do they appear at any time, even at rest? Do you get them when you eat?