It's sometimes these GCC fitness can be tough if there is some scaring or calcification. Outside chest X rays may not help. Good test will be do plain CT scan of chest and find what exactly is there. If CT shows some calcification or opacities, then I will suggest you to look for other countries option for work.
Get a CT Thorax/ better will be plain HRCT Thorax for better results.
Next Steps
do HRCT Thorax plain
Health Tips
I have seen quite few cases who get rejected.
give CT a try and find out. all the best.