i had a hardcore flu during first 2 weeks of exams, coughing, running nose, body aches, headaches but now its all healed
I suggest you get at least 8hrs of sleep, drink OJ, no fried food ofc, eat healthy (like soup and stuff - if you cant handle the blandness of it, eat it anyways), drink heaps of water (i drank around 5 bottles of water a day, 750mL ones)
Before exam, eat something like soup or porridge, then get some robitussin too (DONT OVERDO IT, IT has DXM which causes hallucinations
)