Hello dear Entrance exams include competition at state or national level which irequires a lot more hardwork , dedication and time than the school time studying. As you have mentioned that you were a good scorer in school, you can try to improve your learning methods, sources of information and also give more time . Try looking at previous year question papers, take guidance from your teachers, practice papers and make a time table by dividing your study material with sufficient breaks in between. Try meditation to improve the your concentration and also make daily targets and work on it. Also spend time with family and friends to uplift your mood and take their advice as well for career planning.