This is a somewhat complicated situation. You should ask Your husband’s pulmonary doctor about how the pneumonia and the paralysis might be related. There are many causes of paralysis of the diaphragm. It may take the combined efforts of the neurologist and a pulmonologist to decide what the next steps should be. Paralysis is a common occurrence and, depending on the cause, not infrequently spontaneously reversible.
Your husband’ss shortness of breath will improve with resolution of the pneumonia but his lung function will remain somewhat diminished if the paralysis persists.