Whooping cough as a post-viral phenomrnon. Breath shortness, lack of sleep?

Possible. Two simple tests, the direct fluorescent antibody (DFA) test on the nasal secretions, and CBC with differential, as well as the 3 classic symptoms - 1) 'whoop' noise with inspiration after cough, 2) paroxysms of coughing, or many back to back cough episodes without a break, and post-coughing vomiting, all help to make the diagnosis.
Not well yet. See your doctor again. There may be residual virus or another problem. An exam, naybe ests will Dx. More Tx is needed to ease breathing. Don't delay. Older folk can take more effort and time to recover from illnesses. Best!