Its not normal at all , your mother should really see a doctor !
I am a 30 yr old mother of three. I have been on my period for over two months. My OB/GYN has started me on birth control pills (even though I already have an IUD) & iron pills. They say it is not unusual to have a period for up to 6 mths straight.
I would advise u not to worry too much. But, if u find out something more or if I do, lets's post on here for other people who might be going through the same thing.