I'm seriously so freaking annoyed. My doctor wrote me a notice of leave for school and I got an…

I'm seriously so freaking annoyed. My doctor wrote me a notice of leave for school and I got an email saying that since it doesn't have a duration of time I'll be out they won't except it and my doctor needs to fax an excuse to them with how long I'll be out for it to count. I'm seriously about to just drop out again