As far as i  know you wont  be able to do anything on your visa until it is expired.i wont go to mexico since it  is harder to get a extension  from there.Canada is a good option  but  again the  chances are 50/50.if you really decide to go to canada for extension make sure all your documents are strong and you should provide them  with a strong reason why u wanna extend your visa.if you have changed your  major after entering the u.s  it might help  u because u can tell them that your  new major is going to take longer time  than  you thought,so u wanted  your visa  to be extended.Good Luck.