How to recover from cough/throat phlegm quick?

There are solo auditions for my choir tomorrow, and I've been practicing and dreaming about getting one of those solos since our choir director told us about them. However, lucky me, I got a cough two days before the first audition date. I used to have a fever, but that has mostly faded and now I am fighting mostly only excess throat phlegm. The phlegm in my throat is making me unable to sing without sounding all raspy when I try to raise my volume to how I normally sound. Are there any methods I could use to remedy my sickness quickly, in preferably 1-2 days? Thank you so much for answering.