Why does my cough after taste, taste like metal? (Coughed a couple of times in the past two days though). Mucus this morning was little yellow.

See a doctor. the metal test after a cough could be concerning because sometime it could be the test of iron and that could mean that there is a blood might not be visible in you sputum so my advice go and see a doctor will examine you either will assure you or treat you of course there is a lot of other theory to explain the metal test as well good luck.