Shaykh Ibn Uthaymeen was asked:
Oh Virtuous Shaikh, if a student who is hardworking in memorizing all his lessons is sick on the day of the exam but he attends the exam [and as a result] his sickness increases, is it allowed for one of his brothers to assist him in exam? Or what does he do?
“it is not allowed to assist him in the exam. However, if it reaches a state in which he is not able to answer, then it is a must to look at his condition. Either he is given a mark according to the average, that is, the teacher looks at his total [mark] in the other lessons, then he is given [a mark] for this material similar to this average. Or he repeats the exam in accordance to what the system requires and what the administrations sees or the dean”.
[Taken from: Liqaa ash-Shahri no. 24]
Faisal Ibn Abdul Qaadir Ibn Hassan