I would stay away from all meds. It is completely normal to feel nauseous, dizzy, and shaky before giving a presentation in front of your peers. You need to talk to your teacher. I am a teacher and I accommodate my students everyday. Also, you should let your parents/guardians know how you're feeling. When I was in college, I let my instructors know that I had anxiety about speaking in front of people. Everyone of them would "accommodate" me in some way. Usually, it was by letting me stand near the door, or letting me go first. Also, standing behind a podium or projector, or presenting by walking around helps. Having information to pass out to your audience helps too. Anything to get moving and get that extra adrenaline out is most helpful. Try to focus on a friend that is watching. Let them know you need them to reassure you while you're presenting. I now have to give presentations in front of 100+ every summer...I still feel terrible before hand, but once I get going, it subsides. You don't want to have to medicate yourself. You want the information your giving to be believable, and medication would definitely hinder that. You have many years ahead of you, so learning techniques to cope now is the best way. Good luck on your presentation. You'll do great! Let us know how it goes.
Walgreens is a poor place to search for herbal remedies. It's not what they do well. St. John's Wort is mostly for depression, not anxiety. Valerian is a poor idea because it might make you drowsy and you won't perform your best. At your age, I'd have to agree with the former answer, this is something to work on and get better at rather than medicate it. There are public speaking classes you can take expressly for this purpose. Also remember that presentations in class are practice -- yeah, they count for something in your grade, but their purpose is to practice so you get better and more familiar with it. What you're feeling is quite common. Now, there are natural remedies that can help, but again, you're young, this isn't a chronic problem, it's a new problem, meaning you haven't been doing it that long. The more you do it, the more you'll naturally overcome your anxiety about it, or learn to cope with it (a little anxiety gives us some adrenaline when we need to perform). And you'll also learn you don't need to turn to a little pill every time you're nervous about something. Now, if you have a real chronic anxiety problem, that's something different; for that you would want to see a therapist and a naturopath or homeopath if you wanted to try natural remedies. Good luck, though you probably don't really need it.
And I'll just add, since you're 16 and you're going to do what you're going to do anyway, the only thing I'd recommend is a cup of chamomile tea. It's also calming to the stomach. Very mild. But test it on yourself first to make sure it doesn't make you tired. I mean, unless times have changed since I was 16, you probably don't sleep much anyway.
Thanks, both of you. I ended up not taking anything and things went okay. I was told I said "um" too much, but other than that, it wasn't too bad. Thanks for the advice. :)