Addition Facts

Josh finally passed his #6 addition facts! His teacher sent a note home last Friday-she wanted us to work on the 6's. Apparently, Josh has a nervous breakdown when he takes the test. So we worked all week. I gave him a practice test on Thursday and he about fell apart. He gets so worried about the time, that he can't concentrate. The more he practiced, the more his confidence grew and he did not seem to get so nervous. If anyone has any advice on how to calm his nerves please let us know? I have tried everything. HELP!