I have quite bad social anxiety - but it varies. I used to have to give talks at work and when I did them my throat would lock up like you describe - I could barely speak. It was so embarassing. I hate public speaking.

I also used to get it when I was much younger on places like the train. If I felt particularly anxious or self-conscious I would start to constantly swallow. The more I thought about it the worse it would become.

It rarely happens now but if I'm I'm feeling very vulnerable I can still sense it there in the background - a horrible feeling.