Great question - social anxiety like yours is actually rather common (more common than you would believe). Thanks for writing. You really asked two questions, and I will address each of them, in reverse order.
(1) I'll answer the second question first: There are absolutely medications which can help to ease some of the anxiety that grips you when you perform. If you notice the symptoms somewhat irregularly - or, not very often - then you can take a class of medication called a benzodiazepine (like Xanax, for example) about 20 minutes prior to the event, and you should be fine. If the symptoms are going to interfere in your everyday like, then an SSRI (like Paxil, for example) can help long-term to ward off social anxiety without the risk of addiction or tolerance.
(2) Your first question is a bit harder to answer in a short forum such as this. Basically, what you are dealing with is an early sympathetic arousal. In other words, your "fight or flight" system turns itself on earlier in social interactions than for other people, and perhaps in a more pronounced manner than for other people. Your task is to work to re-engage the parasympathetic nervous system to ward off the effects of the sympathetic. And while this seems rather simple, the process itself is anything but. Here are a few suggestions:
(a) remember to control your breathing. Deep breath in... let it out slow. This will help to engage the parasympathetic response; (b) find the negative thoughts racing through your mind that may serve to handicap your interactions by giving yourself messages about failure. Replace them with neutral thoughts that can arrest some of the toxicity of the original thoughts. My guess is that your mind goes into "vapor lock" once your anxiety starts to spike, so tuning in to the thought process may help you to remain present. My initial recommendations on replacement thoughts for clients are always either "I'm okay," or "I will get through this;" and (c) this one sounds a little corny, but can work to help you reflect some appropriate modeling: Think of somebody who is able to interact with others in a manner that you admire. Use a guided imagery to go over their every move, no matter how subtle. Then, act "as if" you are that person. Take the endeavor completely out of your hands, and merely "put on" the persona of the other person.
In general, a therapist can help you out with this problem and will be able to speak to your physician to help with medical management. If you have questions, they can also be a fantastic resource. I wish you well! This problem should be manageable in a short time - If you are satisfied with the response, please hit "Accept." That is the only way I receive credit for my answer. Thanks-