my husband experienced stomatitis & hand foot syndrome too. when it became too severe, his doc ordered him to stop until they healed, and then go on with a reduced dose, and he is doing well until now.
you may try gelclair or magic mouth wash or soda solution rinse for the stomatitis, they worked well for my husband.
there are also some information about the side effects of nexavar in previous disscusion in june or july, you may check them.
Good luck, god bless you