Why is my stutter happening only at school

Why is my stutter happening only at school So I stutter I’m 16 and I don’t have the worst speech but sometimes I mess up bad and sometimes I do good like I can order food ask instructions or things that require 1 on 1 speaking or anything outside of school but when I’m at school my throat feels sore closed like I can’t even talk loud even if I wanted to, I had orientation today and I had to say my name and I could barely talk loud but outside of school I can say it perfectly l