How do I proceed when my doctor won't see me for an ongoing problem?

I should start out by saying that I have a lung disease called COPD that I have had for almost 20 years. (no I do not smoke, it's origin is unknown) Beginning in Nov 08 I was having problems breathing and went to my lung doctor and he did the usual, xray etc. and told me I had bronchitis and put me on steroids and antibiotics. When I wasn't getting any better after completing the treatments I called him back and he again did the usual tests and said he could not see a problem but he put me on a different antibiotic and sent me home with instructions to call back if I did not get better. This went on through January, and I saw him a few more times before this point, At the Jan appoint my mother and daughter went with me to see him because everyone was getting concerned at his inability to do anything but the usual xray. At the end of the visit he told my relatives that it was all really in my head but he sort of chuckled like it was a joke; however, he had already said that to me several times during this process. He again says he cannot see a problem and is getting ready to send me off again with no real help but I asked him to get me an appointment with a cardiologist to see if my heart was causing the shortness of breath. Well lo and behold I had 3 blocked arteries and had to have 3 stents put in. Long story short, that procedure was in late February and while I was in the hospital I got pneumonia for which the doctor gave me more antibiotics. Now I find I am still having a very hard time breathing so I call the pulmonary doctor and ask if he can get me in to see what is going on and his nurse calls back to tell me the doctor wants to wait until my scheduled appointment, which is May 6th!!! What in the world am I to do about this. Can he really refuse to get me in? It takes months to get into a new doctor and I am moving 350 miles away the first of May. I am at a complete loss here, not to mention worrying about the strain on my heart from not breathing well. Can anyone give me some guidance?