Why is my mind not absorbing anything?

Okay so I want to study but my mind isn't really absorbing anything (brain-fogged). But I have tried everything :

  • I eat healthy (I even gained like 2kgs weight - I don't eat fast food now a lot)
  • I sleep atleast 7 hours a day
  • I drink coffee (but only once a day, usually around 5-6 hours earlier to bed)
  • I do breaks and proper studying
  • I even quit f@p 12 days ago
  • I stay hydrated all the time

I do all of these yet still my mind doesn't seem to be absorbing stuff, and even if it does, it's short term and not quick at all. What can I do to improve this?

I have my exams in about a week, so please help me out with this one.