Chronic Fatigue and drowsiness. I do?

Few months back, I was diagnosed for moderate depression and severe vitamin deficiency (B12 and D3). I have taken 2 Methylcobalamine 1000 injections and a followed a three month course of T nurokind OD and Tayo 60000 IU ( once a week) tablets. But this exhaustion and daytime sleepiness isn't cured and little to no improvement is seen since the diagnosis even after having a balanced diet and morning workout. This heavily affects my classes and studies. As, I have my end sem exams in June, I asked a known pharmacist with my deficiency prescription for Modalert 100. He gave me one strip of tablets and insisted to take 50 mg two days once to avoid withdrawal. I feel normal with no tiredness or exhaustion. But my psychiatrist insists that I have depression and diagnosed me again for depression and prescribed me fluoxetine 20mg. He doesn't want to prescribe Modalert and asked me to get a second opinion from another psychiatrist. What should I do?