Question

When you fall ill during final exams. How expand this theme?

Answer 1

This wouldn't expand the theme but would continue the plot. I think that may be what you mean, but if not disregard this answer. Falling ill would continue the plot because if you can't go to the exams, then what will you do? Exams are important, so its likely that the character doesn't want to miss it. Something else has to happen for the consequences to be avoided.

Answer 2

You would have to tell the Procter administrating the test. Immediately seek medical help. Once you see the Doctor they would then need to write an excuse. You could then take the test on another day when you recover. You must in this case be totally above board. This normally would be uncommon for an honest person..