I can play music in front of around 1800 people and have no problem at all. But talk in front of 30 ..oh my god.. Could this just be a comfort thing? Or could it be that in a group situation its easier to be comfortable because I am not the sole center of attention. I've never cared when people watched me play sports either (college rowing).
It sounds like you're more comfortable when you're performing with others than when you're performing alone and you're the sole center of attention. When you're alone, you get more scrutiny because all eyes are on you, and this can feel very uncomfortable.
Because social anxiety and public speaking anxiety are caused by a fear of scrutiny or negative judgement, here's an exercise you can do to increase your tolerance of scrutiny. What you want to do is prove to your brain that little mistakes and imperfections don’t matter. So find opportunities every day or every week to draw attention to yourself in a group of people.
For example, you may want to:
• Shout to a friend across a crowded mall
• Sing or hum while shopping
• Come in late and walk to the front of a crowded room
• Button your shirt the wrong way and go out in public
• Wear shoes that don’t match in public
• Try karaoke with a small group of good friends
• Add your own ideas to this list!