Stammering blocks

Stammering blocks My school final exams will start from February 15 and my prep is going well but since I have stammering , i couldn't ask for supplement/additional copy during the exams . My mind goes blank and i sweat in nervousness before asking it from invigilator , as I keep procastinate it the nervousness keep builds and in the end i feel so overwhelmed that I give up on asking for additional . Please somebody help I don't want to get fail in my finals ( sorry for bad English)