ER or Not? (Slightly tmi)

I caught a chest cold over the weekend from this annoying Chicago whether. I've only been sick for about 4 days but now it's progressed from a hoarse throat to a painful chesty cough. And this morning and yesterday morning I coughed up green phlegm with some streaks of blood. My doctors nurse instructed me to go the er but my mother and boyfriend would prefer me to wait it out. What should I do?