Too ill for exams

I've been suffering from a skin condition for the last month or so. It's made me being unable to sleep as even the potent anti histamines won't stop the skin from flaring or having a burning sensation. This lack of sleep has caused me to become disorientated and caused minor memory loss. My gp hasn't been able to help me and i've been referred to a specialist at my local hospital. If the condition worsens or prolongs untill my exams start , what can i do? My head of year says i should be given mitigating circumstances , but isn't that for after exams? Help pls

why dont u talk to the exams officer and exam boards??

My exams officer is already notified , i could call the exam boards i guess ty for advice.