It is not guilt as many people have said. It is self-loathing shame. It is hopelessness. You feel like you can't do even the basics of being human right. You can't talk as easily and trouble-free as other people. I have been there. I have cried at the back of my car after school. Or before that, after the lesson I kept thinking what must all the other people be saying behind my back. I kept thinking like this before I went asleep. Things are a lot of different right now for me. I am the most confident speaking in my class. Public speaking isn't a problem for me. People ask me for tips for interviews. This goes to show that you CAN improve your situation, no matter how desperate you feel right now. I would love to help people with this problem, DM me freely!