Hello,
I understand your concern.
This might be examination funk, that is when your mind is actually tired, there is a possibility of loosing concentration during this phase.
Or this might be simply a change in your behavior due to some disturb situation in your life.
Next Steps
Take the following homoeopathic medications,
Rx,
1. Arg nit 30 ( 2 pills twice daily for 7 days)
2. Rubrum 50 ( 3 pills Thrice daily for 7 days)
Health Tips
Mediation for 20 - 30 minutes in morning.
Sleep for atleast 8 hours.
Have light but nutritious diet, like fibers, proteins.
Avoid carbs, that make you lethargic.
For further medications, consult online.
Stay fit, healthy & positive.