I think what you experience is nervousness. You can overcome the anxiety by thinking positively about the presentation, do some light exercises and activities, be prepared and practice well before making the presentation. Visit http://www.wikihow.com/Overcome-Anxiety for more tips.
I had a similar problem when I was a teenager, it was so embarrassing & that just made me redder. I used to get teased about it which also didn't help. It took me years to get it under control & now that im older I realize that it was all about self confidence. Take some deep breaths, don't panic & get it under control. The worst thing to do is panic because it builds & builds & gets worse. Good luck :)
For some people they can practice and get better, but for me, I stopped caring what everyone thought of me and it let a lot of pressure off. I also thought, well nobody will even remember by Monday( because usually we give presentations on Thursday or Friday ). Most people don't care how you do on your presentation and while your doing it, they might be like, wow you stink, or, wow that was really good! You just need self confidence, or to stop caring.