Dear Peter,
I'm sorry to hear that you've come down with a headache and a fever. I know it is the reason why you didn't do well in the English exam. However,there is no need to feel low. I'm sure you will do a good job later on. It is necessary you go to the hospital and have a good rest. Drinking more water may be helpful, too. I hope you can recover soon and have a good result in the next exam!
Yours,
Bob
亲、虽然帮你写了一篇但是作文这种东西还是要多练的哦、毕竟中考也是要写的嘛^ ^