However, there are many causes of sudden hard
coughing, one of which is what is called Gastroesophageal reflux disease (
GERD or “heartburn”) that irritates the larynx (voice box). In these instances, treatment of the GERD can often reduce or stop the cough, and thus prevent the seizures. The seizures, by the way, can very much resemble epilepsy, as your description suggests.
Your description, especially of his medications, also suggests that he may have COPD.