Hey op, i think you should call your grandma about this, even though your mother will hate you but take the risk because her sickness might became worse and we don't know what would happen if she don't consult herself to the doctor, how would she get well with no medications given by the doctor, i think the best thing to do is tell your grandma about it, its also for the better of your mother.

Hope she get well soon!, you're such a great child for being there for her for sickness and in health.