I am in teaching profession. Teach in school. I can't speak loudly generally after recess or 1 hr of continuous lecture. I don't know the correct reason. During recess I have only tea n some homemade food which is not at all oily. I feel pressure in throat and cannot dictate or explain in loud voice What should be done to overcome this. I feel stress to say a single word loudly. Even the child sitting on third bench cannot hear me.