hi, I'd recommend Bach's rescue remedy....I know lots of people who swear by it and it comes ina handy little bottle that you can carry with you if need be....
i would buy an A4 lined pad from partners stationers as they are cheaper than W.H. Smiths , and i would divide the page into two columns, and then in one column i would write a list of all the fabulous things that have happened in your life and then in the other column i would write,to be continued and then see if you feel better.
have a chat with your doctor - propanalol (a beta-blocker) is good for dealing with the heart-pounding, shaking, sweating kind of nervousness. other, more "human therapeutic" types of solutions can involve the Talking Therapies, such as Cognitive Behavioural Therapy (CBT) which can sometimes better address the problem. (in my experience, a bit of disinterested human input can often be the best first step). otherwise, there are other options, but it depends where the problem stems from...
I'd go with BuckyKat and try bachs rescue remedies, if you go on thei website you cna find a remedy which is suitable for how your feeling!
Also try Kalms, I've used those too and they've really calmed me.