Blood in Mucus

I am in the process of getting rid of a cold and for the past couple days I have been finding blood in my mucus when I blow my nose. It subsided for some time but returned. I have no clue as to what it could be and this has never happened to me before. What could it be and what should I do?

[National Jewish Health]

Bloody nasal mucus, with an upper respiratory infection, is not uncommon.  If this is just a cold, it should subside shortly and, with it, the blood in your mucus.  If blood, in any form persists after the cold symptoms are gone but not before, you should have your nose examined.