Inform your tutor that you missed the exam and the reason why. Add that you have booked an appointment with the GP and get a letter confirming the same.
It would have been helpful if you had informed them before rather than after the exam.
If you have an exam today go and sit it if you are in a fit state to do so. If not let them know.
Go and see your GP when available. Dont worry they deal with such situations all the time.