It's normal, it's anxiety. Most people have a fear of what they may face so you just don't want to really confront it. Your body gives off warning signs to this, it's why some people when they make speeches they have such a great fear that they may just vomit upon stage. I'm not sure about the extreme measures of anger having the same effects, but I'm sure each person has some way these things work. I'm sorry I couldn't help you much more.