Talk to General Physician on Shortness Of Breath And Chest Heaviness

Mri mother ko kch days se sans MN masla hota ha jb kch ziada kam krain or stairs ky 2 chakar lga lain pir bi ho jata or sath mn chest bi bhari bhari hoti jb suba utha jata.. Un ki normal saturation 98-99 rhti par jb kch kam krti ya stairs se chakar lga kr ati to saturation 80 pe chli jati.. Kindly doctor suggest what problem and what we do now?