For me, nerves are a mind game, and tend to arise when I'm worried about what someone or some people will think, and it's that focus that can become problematic for me. I know it sounds twee, but the gospel actually really helps me remember that my worth is not caught up in my performance. Did you see this: http://www.limelightmagazine.com.au/Article/329982,simon-says-i-admit-to-doping.aspx ? Some took it seriously, which was amusing.
beta-blockers - work a treat to slow the heart rate over a long time period but I wouldn't expect them to be an instant reaction drug (based on how they worked for me post heart op and how long it took to be 'weaned' off them).