I have completely same problem with you, and automatically get nervous when talk with someone in formal way, i am afraid to get embarrassed, afraid to make myself a fool, and don't feel like i am normal human being, it's very hard and this feeling it kills you inside, and i am very sorry, but i don't know how to avoid your fear of talking in exam, you can either try some medicine, or try to be calm about it (yes i know it's cliche, but there is no other way) stutter is something which can be reduced, if you stay calm, i am trying to do it, and sometimes it actually works, also while talking you shouldn't think about that you wanna end it as fast as possible, cause if you will think like this, you will want to speak faster, thus stutter more, so you have to speak in normal pace (not very slow, and not fast) i am sorry for such advice, you probably heard it so many times, but it's either this or drugs which can be dangerous