You can use syrup lupituss 2 teaspoonfuls thrice a day but this is also not the definite treatment. Consult your chest physician ASAP as cause of cough needs to be evaluated
Next Steps
Get a chest x Ray done and if you get any phlegm get it tested for tuberculosis or other infections (Sputum for afb, gram stain and culture)
Health Tips
Watch for blood in Sputum fever or weight loss