Have You?

is it when you become "mute" in uninteresting situations ?

Do you have selective mutism?? Shocked to hear it/ It sounds like you may have an anxiety disorder of some sort. I have experienced similar things, when I was suddenly very afraid to say something to someone I knew in public or where I had very bad shortness of breath when trying to speak in a meeting, so that I could hardly speak and had to apologize then take a moment to catch my breath. This despite being a teacher and acting in front of thousands of people. I think you should talk to your doctor who may refer to a psychiatrist or prescribe something for you. Especially since it sounds like this is very debilitating for you. Best of luck. You sound like a really nice person. Remember you deserve to be heard! :)