Answer:
Bipolar disorder
Step-by-step explanation:
Bipolar disorder, also referred as manic-depressive illness is a mental disorder in which a person experiences extreme mood swings that ranges from high to low, and vice versa, unusual shift in energy levels, etc
Highs mark maniac period, whereas lows are depressive periods.
Sometimes, these mood swings become mixed, and a person might feel both depressed and energetic at the same instant.
Thus the case of Malik where he was depressed for 2 weeks and then suddenly shows so much energy and unusual behavior represents the case of Bipolar disorder.