Suggest Treatment For Depression And Anxiety

Hi, I am Banashree Ghosh. I am studying Mathematics Hons In M.Sc 1st year.Upto 2nd year in college I was topper. But nowadays I am frightening from my study. In fact I have left the institution(IIT Bombay) due depression. Also last year my result was not so good. I don t know what s wrong with me? Please help me