Can't Clear Throat! Stupid Mucus, any Homemade Remedies?

Okay, so I'm going into my school talent show with singing, but all year I just cannot get rid of this stupid phlegm-mucus, or whatever it is. I haven't been sick, but I have been having to clear my throat constantly and nothing comes out, and I have really bad allergies (it's sinus drainage!), so that must be the case. Often my nurse tells me to gargle with warm salt water. But that only gets some of it, and this throat junk is preventing me from singing well, so I was wondering if any of you guys knew any HOMEMADE remedies (i'm only 13, and I don't want to bother my parents for money unless I truly have too.) Please help me!!!!