Answer:
I can answer that! In fact, I have SM, Selective Mutism! It is where u cannot talk in certain places and you need help, it is your anxiety. In fact, I started to talk in school in fourth grade & probably whispered in third. I am in 6th now and plus I got help back in first or second grade bc I didn't understand. I am autistic. And... yeah!
Here is a better understanding:
"Selective mutism is a condition in which a child can speak, but then suddenly stops speaking. It most often takes place in school or social settings." from Bing
Also:
What does it feel like to have selective mutism?
"Selective Mutism can feel like a burning golf ball is stuck in your throat blocking your words from escaping. It is painful; you can feel frozen, in shock, panicked, and embarrassed. Many times tears will fall."
Yeah that is true, too! I hope I helped you, have a nice day!