I been having sharp stomach pains for a few days. Yesterday was particularly bad, I managed to finish an essay that was due the day before but when I went to university to sit for my exam, before getting there the pain got so bad that I had to go back home. 
I called the dr this morning to try to get an appointment but at my practise the standard procedure is for a dr to call back and do a phone assessment before deciding if a patient needs an appointment.
I don't know what to do, I won't be able to proof mitigating circumstances will I? Will the university just let me re-sit anyway?
The dr just told me to take pain killers and didn't want to see me.
The exam is for my most important module, which I can not progress for its continuation next year.