You may well have sinusitis and some of the phlegm could be originating in the sinuses. But, the
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Primary lymphoma of the brain source of your sputum and the brownish grayish specs is most likely chronic or subacute bronchitis, due to cigarette and cannabis smoke. This is not a good sign, especially at your young age. It suggests that your lungs and bronchi are quite sensitive to the toxic effects of the smoke. Because of this sensitivity, it is quite likely that, should you continue to smoke, you will develop chronic bronchitis and emphysema, also called chronic obstructive pulmonary disease (COPD) at an early age.
Should you quit smoking now and not smoke in the future, the odds of preserving your lungs will be in your favor. This is a critical time in your life, when you have the chance to avoid COPD, a dreadful disease that will shorten your life span, and in the process, make your life miserable. You should work with your doctor to get and use smoking cessation medicines, of which there are 3 effective types. We also suggest that you call the national Quit Line at 1 (800) QUIT-NOW (784-8669).
Good luck.