Try lying on your stomach and leaning forward when you have trouble breathing - it really helps me!
Last time I was in the ER for breathing problems, I had a doc who actually knew what mg was because he had worked with a surgeon who had mg. He told me to lean forward and it definitely helped. He explained I was using gravity to help me breathe instead of fighting it by lying on my back and having to push my lungs against gravity.
Now I do it all the time. It doesn't stop the problem, but it definitely helps me breath easier!