Related to Asthuma. So we got confused!

Hi ,My father in law since 5months he have breathing issues and suddenly feel weak while walking but doing his regular duties he is basically A farmer now managing cows ,He had a habit of smoking before a decade after that he quit it ,he doesn't have sugar or pressure or any other health condition his x ray shows normal ,HB also quit good CBC also good But sometimes gets worse so we took him to 4doctors all of them said all r normal just don't sit in cold climate and drink warm water so again we took him to govt hospital there also same but they gave medicine related to Asthuma he doesn't have severe condition but when we check SpO2 it's 84% After resting few minutes it came 93% So doctor continue to medicines  he don't have any other problem expect breathing issues while walking Now the problem is doctor prescribed him Salbutomol and Etyphylline Theophylline,Bcomplex and citrizine But the same hospital pharmacy gave prednisone and etyphyille and Theophylline so we got confused