Lung or breathing problems can develop several months to years following a bone marrow transplant. In some cases, these breathing problems develop without any signs of germs or infection in the lungs. The name for this type of breathing problem is called "Sub-Acute Lung Injury". Sub-acute lung injury often develops many months, even years following a bone marrow transplant. It is often characterized by shortness of breath, cough, wheezing and fatigue.