I am having difficulty breathing. I feel shortness of breath, tightness of my rib cage, and I have chest pain, back pain, but this is sometimes. I have seen a heart doctor, gotten tests done. He said that I have PVCs and some galloping but I don't have asthma and he said I may have some anxiety. I feel like I am not getting enough air to my lungs and it really hurts under my shoulder blades on my back. I don't know what to do and have been experiencing this ever since I was about 12, I am 18 now. What could it be or what should I do?