Exam stress is fairly common. Certain steps might help : 1) get a timetable for exam studies. 2) take regular breaks. 3)revise whatever you study. 4)Don’t pressurise yourself. Try deep breathing exercises. Dont lose hope.

Hii, its normal if u have difficulty in concentration while studies sometomes worries made dis too. So just keep trying u have backlog its ok any person at ur stage can feel the same if he or she have backlogs dear so dont loose hope just keep trying pratice makes a person perfect exams are our part of life if u have failed in tge the past doesn't mean u will fail in future too ok all the best  keep trying ok