My dad is coughing a lot someone help

So my dad is 55 years old and hes been on dialysis since April, he barely survived. His energy is better since dialysis and his appetite and everything is better except his coughing. I should mention that he smokes and has been smoking since he was like 17 BUT it was never this bad. since he started dialysis his cough is awful and he cant stop it, and on average he starts coughing every like 5 minutes and its not a dry cough and it lasts for at least a minute. is this normal and should i be concerned because its really starting to worry me.

also i know that some people said that it might be some like blood pressure pills but i dont think that it is because of that.