She should take an iron pill every day so she doesn't get anemia, and should make an appointment with her doctor. If this was her first period (can't tell for sure what you mean when you write "for her first time,") it might have a simple explanation, but it is still worth checking. The doctor might want to do an ultrasound to check to see if she has a fibroid, though that would be unusual for if it is her first period, since fibroids are not usually seen in people that young.