I have been struggling with lung issues for over 2 years. In Dec 2012 had a lung biopsy to determine it was HP. I have been on Prednisone since the end of January/13, (up to 80 mg) and no success. Had my house checked for air quality, have installed hepa filters in my house and still no improvement. Actually getting worse. Able to walk fine, though o2 levels drop to 75%. What can I do to find out what is causing this? Seeing rhumatologist and allergist at the end of August.