If you have some patches on your lungs, you are going towards a difficult life for about half year to one year in Qatar. And this is if you are lucky.

Lung patches means lung damage, most probably caused by TB. You should investigate this further BEFORE quiting your job.
Make some sputum and skin test for tuberculosis. If they will come out positive, it's a big chance that your residence permit will be rejected, and you will lose your current job and the new one.