I have a really bad cold & so I cough alot & whenever I cough I cough something up sometimes its clear & sometimes it's yellow or green.
What I'm coughing up???
What is the clear stuff called???
What is the yellow stuff called???
What is the green stuff called???
The only thing I could think of was that it's snot but that seems really weird to be coughing that up & nasty

Also whenever I cough something up should I swallow it back down or spit it out???
If I should swallow it back down than why???
If I should spit it out than why???