My boss is racist to me but not in a obvious way?

i work as a cleaner in a school all the cleaners are black apart from me and a morrocan guy my boss keeps moaning at me saying my rooms are not clean and always has to complain about something everyday she is rude all the time and orders me around. the other day the morrocan guy came to help me hoover a room and my boss came and started shouting saying dont help her you only help everyone but her. i think its because im white she is being this horrible what do you think?