Given the very brief history that you have mentioned about your mother's problem, possibility of COPD or Asthma & whether any underlying heart disease is there, needs to be ruled out.
Treatment will depend on what the specific underlying problem it is.
Also, she should receive vaccination, if she's prone to frequent respiratory infections.
Next Steps
She needs to get her CBC with ESR,
CRP, Sputum culture & AFB, Chest Xray, ECG, Pulmonary Function Tests & Echocardiography.
Health Tips
It's better to seek Medical aid at the earliest & not prolong it too long.