You can be in a mild phase of depression and lack of concentration. Eat a wholesome diet, exercise for 150 minutes/week and join a gym or go fir swimming.

Dear this can be handled by understanding your potential and then Taking up the action in a realistic  and achievable measures.

Loss of interest, decreased concentration and attention, feeling low and disturbed sleep or appetite are some of the signs of depression. Consult a psychiatrist who will assess you in detail. If you are feeling suicidal or hopeless, seek professional help immediately. Try some relaxation techniques like yoga, meditation and deep breathing. Indulge in hobbies. Spend time with people close to you.