Ughhhh, I'm still sick. How do I clear my throat?

I'm worried I might have to skip school tomorrow....I have this cough and a sore throat and my throat is like all clogged up and I can't talk well. Sometimes I'll have to cough like 20 times before I'm able to talk. How can I get better by tomorrow? How come it's so hard to clear my throat? I mean I can't get the phlegm or whatever out (I can't spit it out cause it won't come out). Do I need to skip school tomorrow? I also have to present a project at my last cl, and I kinda need to be able to talk.......