There are a few threads here dealing with how to follow one's dreams. Sometimes these dream may be in conflict with one's schooling. After all Mark Twain once said,
'I have never let my schooling interfere with my education'
I say that you would probably be serving your self and the world the best if you focused on songwriting.
If you would like to change majors that's an ok idea, however, classes just by their nature take up a lot of time and effort, as well as intention. Could you focus on both songwriting and classes? I could have done the same thing, but I knew that the screenplay I was writing needed my full attention and intention, and not just a couple hours a day. It is akin to taking care of an infant, you can't just leave it for any length of time, you must tend to it always. The same with songwriting. If you would like to start a career in music then I suggest you focus on it totally. You must be able to eat, sleep, and breath songwriting - not just for short and sporadic periods of time.
I hope this helps. I wish you the best. E
