Dear ####,(您好,###)
I made an appointment with you and explained the reason for my asking for a leave. But my reason was not so serious.
I went back home to have an return visit with my doctor and got the new medical certificate for my sick leave in accordance with the school regulation. On the certificate, the doctor explained my condition in detail and suggested I stay in hospital.
I hope you could help me tansfer my self-criticism to the school authority. It is very important.Thank you.
I beg your reply indeed.Thank you.