About 7 months ago i had a collapsed left lung with chest tube and surgery. burst bleb. every time i cough or sneeze i feel pain in left lung. why?

Inflammation: Make sure you dont have a recurrent partial collapse. If not you may have inflammation of the pleural cavity or irritation of some of the nerves along your ribs on that side. You may need a course of anti inflammatory medications ir evaluation by a pain specialist as you shouldnt have pain this late. Discuss with your surgeon

Mgt: There may be residual inflammation or an infection. It is important to see your PCP and to possibly have a chest radiograph to determine if there is an area of collapse.

Adhesions: Scar tissue. The lung gets stuck against the rib cage and the ribs are not fully healed yet, either. You need a good session with the DR who treated your pneumothorax. Coughing much? Coughing blood? Short of breath? Rapid heart? etc.