Cant get a satisfying deep breath for three weeks. clear ct & x-ray. blood ox and bp are perfect. what can be causing it? er said they didnt know.

Need to examine: It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated.

Impossible to tell: here, if ER doctor who examined you along with these tests could not arrive at diagnosis. Sensation of shortness of breath that is not caused by a respiratory problem could come from heart disease or neurologic disease.