Hi
@nisa.yx
You say it's only the last few days that you've had problems - is that right? Has anything changed these last few days? Could you be ill? Have you changed your sleeping times or habits? Or your diet?
What's your blood sugar been like?
I've found that brain work can use up glucose even though it's not physical exercise. Could lows be causing your symptoms? For me, finding it hard to,concentrate and not taking in what I'm reading is a sign my blood sugar is starting to go low.
Apart from that, my tips are to keep hydrated (with plain water if you can), eat well, sleep well - and don't be afraid to speak to your teachers if you're still having difficulties.