i can understand your concern. the recurrent distractibility could be occurring due to anxiety and should be evaluated. intrusive thoughts during studying result in distraction. if remembering the things related to the past and imagining things are causing distress then that is most probably due to anxiety and need treatment. please consult a psychiatrist for evaluation of this problem and for treatment. if there are no intrusive thoughts then supplements containing omega fatty acids vitamin b12 and e can be used to improve the concentration. it will help in improving focus in your case. for further doubts consult a psychiatrist online --> <link>
what should i do to concentrate in my studies?