After getting into the details you gave me,Pneumothorax can be of many reasons like COPD, bronchogenic carcinoma, sarcoidiasis,tuberculosis,
cystic fibrosis (congenital).As you are from India which is a place for epidemic tuberculosis infection.So first get it ruled out by Tuberculin test which may be done efficiently in India.
If there are no other serious symptoms,I think there is nothing to be worried much.Meet a pulmonologist who is expert in lung diseases.